Uganda's declining soil fertility

Uganda is famed for its fertile volcanic soils and its generally agriculture-friendly climate. A pattern of  colonization quite different from neighboring Kenya's meant that Uganda did not significantly have large scale intensive farming and its associated significant, accelerated soil fertility loss, nor the accompanying heavy fertilizer use to compensate.

Depending on one's perspective, the overwhelming reliance on small scale and 'traditional' farming methods is part of the country's problem (relatively low yields) or it is part of Uganda's positives, because the land has remained relatively pristine and 'uncontaminated' by intensive farming and agro-chemicals. It could be a little bit of both, but to agro-ideologues who see things in black and white rather than in shades of grey/gray, you must take a stand and choose one or the other position.

Nevertheless, Uganda's natural soil richness and the relative absence of 'modern' farming has not spared the country from declining soil fertility.

Described by the New Vision newspaper as Uganda's first soil scientist, Professor Kitungulu Zaake is quoted as saying the country is experiencing an alarming loss of soil fertility, and that soil supplementation needs to be paid attention to as a matter of urgency.

According to Zaake, soil fertility declines account for a drop from an annual four million bags of coffee to three million bags. Yields of various type of banana, the country's main staple crop, have fallen from 10 tonnes a hectare to seven tonnes a hectare, according to him, with production sustained by the opening up of new cultivation areas.

Zaake says striga weed, a parasite which chokes the growth of maize and other grains and thrives in poor soils, is spreading widely, further endangering food security. He also says the high incidence of previously unknown crop diseases can also be attributed to poor soils.

What to do? 'Use more fertilizer' is one quick answer. A study quoted in the New Vision report found that Uganda's  fertilizer use averages 1.8kg per hectare a year, way below the average sub-Saharan Africa level, which at an estimated eight tonnes per hectare per year is already considered very low in global terms.

The article: Looming hunger as Uganda’s soils get barren.

African Agriculture


 

 

Inputs subsidy schemes: does easy fertilizer access discourage good soil management?

by Chido Makunike

Malawi can justifiably be very proud of its farming inputs subsidy programme. For several years in a row, it has produced surpluses of the country’s staple crop, maize. Considering the several prior years of maize famine the country experienced, the turn around is a huge achievement.

From the beginning, there have been questions about the cost sustainability of the programme. Last year, the extent of the subsidy scheme had to be scaled back over a diplomatic dispute with and the subsequent reduction of aid by Britain, a major donor. But none of these challenges detracts from Malawi’s success at addressing a key issue.

Good rains fortuitously accompanied the first several years of the subsidy. The 2011/12 farming season is the first one since the subsidy was introduced that the rain season is expected to be below average. It will be interesting to see what new lessons will be learned from the new variable of poor rains.

However, there is already enough known over many decades for some of the adjustments that may need to be made to the subsidy programme to be highlighted.

The benefits of fertilizer are clear. Availability and cost are the key issues limiting its use in Africa. But one of the downsides of ready fertilizer availability and relatively easy affordability is that they encourage laziness with regards to soil management.

Fertilizer’s effects on plant growth are so quick and dramatic that when many farmers know they will definitely have it; there seems little point in natural soil fertility improvement measures. Yet fertilizer use should ideally go hand in hand with other soil management techniques.

Some of the reasons for this fertilizer-caused soil fertility negligence are obvious and understandable. Most small holder farming is a very hard slog for often very little return. For most farmers, it is already back breaking work before you add the additional tasks of maintaining, say, compost. On poor soils where fertilizer is not available, soil supplementation measures may add to the manual drudgery of farming, but the farmer knows s/he simply cannot avoid it if a reasonable yield is to be expected from that poor soil.

Fertilizer, with its quick, direct shot of basic nutrients to the plant, is therefore a very effective, attractive alternative to the harder work of natural soil fertility supplementation. Farmers are well aware that fertilizer cannot replace natural soil fertility. Nevertheless, when fertilizer is available, the reality of their existence makes sole reliance on it by many farmers irresistible because of its ease of application and its immediate, dramatic results.

But a season of poor rainfall like the present one dramatically decreases the usefulness of fertilizer. Fertilizer application must be soon followed by soil-soaking rain or irrigation. If not, the un-dissolved fertilizer will not only be of no use to the plant, if near physically enough to the plant, it may burn it.

Poor rainfall seasons are when the benefits of naturally rich soils are most apparent. Soil with lots of plant matter in it will have many of the basic nutrients even before or without the additional application of fertilizer. Critically, moisture retention is much higher in such soils, which can make all the difference in whether a plant survives until the next rainfall, or wilts and dies before. If and when fertilizer is applied to such naturally rich soil, it is as a fertility boost, rather than as the only means of feeding the plant. Fertilizer used in this way can be stretched out to cover a larger area without sacrificing per hectare yields.

All these well known facts are often ignored in the excitement of widely available fertilizer and the euphoria of ‘bumper harvests.’ Soil fertility caution is thrown to the wind and fertilizer is treated as if it could replace well fed soils, which it cannot.

Fertilizer subsidies are simply too expensive to continue indefinitely. Sooner or later the long term costs of neglecting basic soil fertility will catch up with a country’s agriculture. Good soil management is a process, not a one time event like applying a dose of fertilizer. Unfortunately, attention to soil fertility is usually paid in times of crisis, when compost, manure or mulch cannot be used as an emergency measure for the sudden absence of fertilizer or sufficient rain. Their use needs to be emphasized on an on-going basis, even when fertilizer is readily available.

The poor rains in Malawi and the rest of the region are likely to result in dramatically decreased maize harvests in 2012. But they may also provide another opportunity to remind farmers and governments that regardless of the success of an inputs subsidy, it is dangerous to treat fertilizer as if it could be a substitute for good soil management. Fertilizer use and good soil management must be treated as complementary to each other.

To ignore this in times of good rains, accessible fertilizer and bumper harvests is to simply postpone reckoning with the problems that build up when soil management is ignored. Those problems will become dramatically apparent in times when one or more of the elements needed for fertilizer to produce its results, such as good rain, is missing.

African Agriculture

Tanzania farmers advised on human manure use

by Meddy Mulisa

A group of 20 farmers from Kagera Region, Tanzania who recently visited Kabale District, in Uganda, were highly impressed by the use of human manure. The method is said to be environmentally friendly as opposed to the use of industrial fertilizers.

The farmers went to Uganda to learn agricultural methods being adopted by Ugandan farming communities who engage in sustainable farming.

One of the farmers in Kabale district, Ms Beatrice Twayangga, said, ''By using human manure, I have been able to double the maize production from three bags to 40 bags per hectare,'' she said.

Kabale's Africa 2000 Network Co-ordinator, Mr Polly Mubangizi told the visiting Tanzanian farmers that the human manure has to be mixed with ashes, urine and leaves from certain tree species to provide an ingredient that would not attract harmful insects to attack crops.

Farmers n Kagera region use very little fertilizer on their farms. Data indicates that during the 1988/89 season, a total of 478.1 tonnes of fertilizers were distributed to villages in the region out of which only 159 tonnes were used by the farmers.

In the 1991/92 season a total of 258.05 tonnes of fertilizers were distributed to villages but only 85.2 tonnes were utilized.

Daily News

New insights on fertilizer trees

Planting trees that improve soil quality can help boost crop yields for African farmers, an assessment shows. The results appear in the International Journal of Agricultural Sustainability.

In Africa, it is generally agreed that poor soil management - along with poor water management - is most greatly affecting yields explained co-author Frank Place and head of the World Agroforestry Center. He said that despite chemical fertilisers having been on the market for more than half a century, farmers appeared reluctant or unable to buy them. Therefore, there have been a lot of attempts to bring in other types of nutrients from other systems - such as livestock and plants.

Although it has been known for centuries that certain plants, such as legumes, ‘fix’ nitrogen in the soil and boost food crop yields, Dr Place said that the centre’s researchers had been looking to develop a more active management approach such as FTS (dertilizer trees systems).

Where the farms are larger, for example in Zambia, it is possible to rest arable land and allow it to lie fallow, he observed. But in a place such as much of Malawi, where population densities are higher, they cannot afford to fallow their land; so we came up with alternative management systems where they could intercrop the trees with the (maize).

While the technique is not new, Dr Place said that some of the nitrogen-fixing species used by farmers were probably not the most effective. For example, farmers in East Africa had been using Cajanus cajan (as pigeon pea).

‘’A lot of the nitrogen was being stored in the trees and seeds; so there was an effort to use other trees that put a greater volume in the soil, such as Gliricidia sepium (one of its common name is mother of cocoa),’’ he said.

‘’A really nice thing about G. sepium is that we have been coppicing some of those trees for 20 years and they still continue to grow back vigorously.’’

 

The atmosphere consists of about 80% nitrogen, but plants cannot use it in this form.> Certain plants, such as legumes, have bacteria growing in their root hairs that convert it into a form that plants can use. This form of nitrogen is know as ‘green manure’ and is a nutrient that helps plants, such as food crops, to grow.

However, Place acknowledged that there were a number of challenges that had to be addressed in order to maximize yields. For example, some systems suggested planting rows of trees between rows of crops with mixed results.

‘’We realised that there were a few management problems with that sort of system - what tended to happen was that there was too much competition between the crops and the trees,’’ Dr Place explained. ‘’We developed a new management system where the trees were cut very low to the ground at the time you are planting the crop so then there was no light competition.’’

‘’The trees go into a dormant state when you cut them like this, so the root system is not competing straight away for the nutrients, so the maize is free to become established. The trees only really start to come out out of the dormant phase when the maize is already tall.’’

Another challenge was to provide enough seeds in order to have mass-scale planting. He said that balancing the provision of high-quality seeds with large local engagement was another hurdle that had to be overcome. ut the rewards in improved yields were noticeable, he added.

‘’Some of the studies have shown that in TFS across Africa as a whole, yields are doubling or more in two-thirds of cases.’’

Where the systems were not delivering such good results, Dr Place said that scientists were looking to refine current practices and modify them to suit the local conditions.

As well as helping to boost yields, the use of trees in agriculture has other benefits - such as helping to ‘’climate proof’’ agricultural land. One example was the use of Faidherbia albida (common names include winter thorn and apple-ring acacia) in West African arable landscapes.

‘’It has a deep penetrating tap root, and it can secure a good water supply even in dry years,’’ he explained. ‘’Generally speaking, tree roots do go much deeper than crop roots, so it is recycling nutrients and water from deeper reaches.’’

There are also studies showing that these roots act as conduits and bring up water to surface root systems (such as those belonging to crops).

BBC

Lime use improves maize harvest on acidic Kenyan soils

by Isaiah Esipisu

As the world’s worst food security crisis continues across the Horn of Africa, including in Kenya, some smallholder farmers in the western part of the country are still feeding their families with last year’s abundant harvest.

This is thanks to an agricultural programme focusing on reviving the fertility of the soil in the region.

According to David Mbakaya, a soil scientist at the Kenya Agricultural Research Institute (KARI), early findings from on going research established that the soil in Western Province was too acidic for maize production due to climatic factors and the overuse of nitrogenous fertilisers.

"From field trials we have discovered that the average pH levels in soil within the region stands at 4.5 – meaning that such soil can hardly support growing maize," said Mbakaya.

Maize can withstand mild acidity ranging from 5.5 to 6.5.

Research scientists at KARI – Kakamega branch, with funding from the Alliance for a Green Revolution in Africa, encouraged farmers to neutralise their soil using lime - a soil additive made from pulverised limestone or chalk. It is cheaply available in Kenya.

"I tried liming my land for two seasons, and the results are astounding," said Isaac Ochieng Okwanyi, a 29-year-old father of two.

Using half of the 2.5 hectares of land he inherited from his father, Okwanyi began growing maize using the same phosphorous and ammonium fertilisers his parents had used for years before him. He harvested four 90-kilogramme bags of maize that season.

But when his farm was selected for liming trials by the KARI team, Okwanyi said, "The entire community, including myself, were very sceptical because we did not believe that what looked like cement (lime) could change anything," said Okwanyi.

"... from what I saw, I can attest that I have never seen such a big harvest in this community," he said.

From one hectare of land he harvested 32 bags of maize, which was far higher than the four bags he had harvested from the same land the previous season.

"The proof of last year’s harvest is evident. I have since moved from a tiny grass thatched house to a nice semi-permanent house," he said pointing to his new house.

Together with five other farmers who had successful harvests, Okwanyi opened a grain bank at the local Sega market, where he and the other farmers withdraw small portions of their stored grain for domestic use.

"We created this bank because of security reasons. With the biting hunger at the moment, it is possible for people to break into our semi-permanent houses in order to steal maize," he said.

He has two bags remaining for his domestic consumption, while his next harvest is only a few weeks away.

There are currently 3,000 farmers from northern Kakamega and 2,000 from Siaya in Western Province on the trial.

Western Province is one of the regions in Kenya that has a stable rainfall all year round. But according to Dr. Marin Odendo, the senior research officer at the Socio-economics and Statistics Division at KARI, the region imports food for six months of the year.

"Most of the farmers in Kakamega are smallholder farmers. Yet this should not be the case because there is growing evidence that smallholder farmers hold the key to the world’s food security," said Odendo.

He is confident that in the near future there will be a huge increase in harvests in the region.

IPS News

The effects of high-input, green revolution crop production in Zimbabwe's smallholder sector*

by H.A. Elwell

Since the 1950s the initial impact of high-external input agriculture has often been remarkable, with large areas once sprinkled with poor crops suddenly flourishing under a green carpet. So dramatic was the impact in certain continents, particularly Asia, India and Latin America, that the phenomenon became known as The Green Revolution.

The foundation of the technology was improved crop varieties dependent particularly on high levels of nitrogen, inorganic fertilisers, pesticides, fungicides and herbicides. The technology could equally have been called The Chemical Revolution.

...half the rice, wheat and maize areas in Third World Countries are now planted to modern varieties, nitrogen consumption has increased from 2 to 75 million tonnes and pesticide consumption in many individual countries has increased by 10-30% during the nineteen eighties alone. As a result, production of food per capita has grown by about 40%.

On the surface The Green Revolution seems to have fulfilled the dreams of the politicians, scientists and particularly of the Chemical and Seed Industries. As recently as 1993, Donald Plunkett, scientific advisor to CIGAR, eulogised the Green Revolution in the following terms:

"...the greatest agricultural transformation in the history of humankind, and most of it has taken place within our lifetime. The change was brought about by the rise of science-based agriculture which permitted higher and more stable food production ensuring food stability and security for a constantly growing world population."

OBJECTIVE OF THE STUDY.

The purpose of this study is to investigate the extent to which Zimbabwe's smallholder farmers have been able to benefit from the high-input technologies of the Green Revolution. This is done by examining the crop production data and background related to the smallholder sector and comparing it to the commercial sector where relevant. The difficulties of the smallholder sector in adopting the new technologies are investigated in terms of the major constraints.

IMPACT OF GREEN REVOLUTION ON CROP PRODUCTION IN ZIMBABWE.

The Two Farming Sectors Under Study.

The soils of commercial farming areas are predominantly deeper, more fertile, better drained and less drought-prone than communal soils. Supplementary irrigation is an important feature, assisting in sustaining yield levels and providing a buffer against drought by enabling early root establishment. Commercial farms are fully mechanised and management standards are high. The farmers have direct access to the top specialist advice of the agro-industry, to markets, suppliers and to credit facilities.

Communal farming is mainly for subsistence with the surplus being sold to the market. The 5.4 million people living in communal lands make up 51.4% of Zimbabwe's population. 74% of all communal land is located in the drier regions of the country.

The soils of the communal farming areas are largely shallow infertile sands, with low moisture and nutrient holding capacities. They are deficient of organic matter and prone to drought. Smallholder farms are poorly mechanised. Most smallholder farmers have no access to even ox draft power and the majority of farming operations are carried out using hand tools. Management standards and knowledge of new techniques are rudimentary. Farmers often cannot raise the collateral needed to access credit facilities and cannot repay the loans from their meagre harvests. Information on agricultural matters is transmitted to them through a long chain of civil servants. Much information from specialists in the agro-industry is lost, delayed, distorted or diluted by the time it reaches its intended source. Access to suppliers and markets is confounded by poor roads, long distances and inadequate transport.

Cropping History of Zimbabwe.

1. Traditional Agriculture.

The traditional system of agriculture practised by the indigenous population before the arrival of the Europeans, and for some considerable time afterwards was shifting cultivation. The fields were...predominantly light sandy soil, which could be easily worked with a hoe, and avoiding obstacles such as rocky outcrops, big trees, compacted areas and stony soil. Land preparation consisted of cutting the trees at shoulder height, clearing the understorey and piling the waste around the base of the stumps.

No attempt was made to manure the ground but wood ash and weeds were dug in. Farmers collected their own seeds from the previous crop. The land was cropped for about three years and then abandoned to regenerate under fallow for about 15-20 years. Crops grown included finger millet (Eleusine coracana), mhunga (Pennisetum typhoides), maize (Zea mais), sorghum (Sorghum vulgare), rice (Oryza sativa), various beans, cowpeas (Vigna ungiculata), groundnuts (Arachis hypogaea), bambara nuts (Voandzeia subterranea), sweet potatoes (Ipomea batatas), pumkins and gourds, cucurbits and tomatoes. Mixed cropping was commonly followed, a practice recognised today as a good soil, moisture and fertility conserving practice as well as a risk-spreading technique. Maize was by no means the dominant crop.

Farming activities were integrated with spiritual, social and cultural life... the "loss" of crops to insects and animals was regarded as an acceptable "payoff" to keep the ecosystems functioning. The fact that no truly indigenous in-field pest control technologies stem from this period, although techniques to control pests in storage, were well developed and widely utilised, probably indicates that insects posed no real threat to field crops.

In pre-colonial times, the population was low enough and the land area sufficiently large for shifting agriculture to satisfy the requirements of the people. But, as the population expanded...shifting agriculture was practised only in the most remote areas.

During the colonial period, the thrust of research and development was geared towards commercial agriculture. Very little effort went into developing technologies appropriate to communal farmers. The prevailing attitude was that communal farmers were (or should be) aspiring commercial farmers and could benefit from any technologies developed for their commercial counterparts. This attitude prevails even today.

Several important changes have taken place over the years in the areas of crops under cultivation and the types grown. The most dramatic has been the replacement of small grains as the predominant crop by maize.

Another major change which has taken place in the smallholder sector has been the introduction of cash crops such as cotton, sunflowers and tobacco, with areas under cultivation rising steeply over...Maize and cash crops now dominate smallholder agriculture in place of many of the drought tolerant traditional food crops grown in earlier times.

2. European Agriculture.

Southern Rhodesia's Department of Agriculture was established in 1897. By 1923, when the territory became a self-governing Crown Colony it had developed into a strong and efficient organisation, comprising of a number of specialist branches.

From the very beginning of colonial history, commercial farms consisted of large holdings. Early settlers used ox-traction to plough the land and the first tractors were introduced between the two World Wars. From the early days of colonialism, maize (open-pollinated) was the most important crop. Other crops of interest to large scale commercial farmers of this period were: wheat, sorghum, millets, oats, barley, rye, rice, tobacco, cotton, groundnuts, sunflower, linseed, sugarcane, varieties of beans, lucerne, potatoes and horticultural crops such as citrus, deciduous fruit, coffee and tea.

History of Improved Seed & Crop Varieties.

It is not possible in this paper to record the historical development of all major crops grown in Zimbabwe, but a few notable examples will suffice to give an overview of developments and help to identify the periods when improved varieties, commonly associated with the Green Revolution, began to impact on the yields of crops in the commercial and communal sectors.

Commercial production of hybrid seed maize started in 1948. Today all commercial maize producers grow hybrid maize...the development and introduction of hybrid maize was perhaps the greatest single contribution made by research to the agricultural industry during 1924-1950 and was, in conjunction with a greater use of fertilisers, and other improvements in cultural practices, largely responsible for the greatly increased yields of maize per acre in the years to come.

Early crop records for the communal areas do not emphasise maize over and above other crops. Indeed, before the colonial era sorghum and millet formed a substantial part of the food security strategies of communal farmers. Larger areas of higher density hybrid maize, often under continuous monoculture, became popular during the 1960's onwards; until, today, the crop dominates communal agriculture, even in areas previously considered too dry for maize cultivation.

The principal reasons for the very rapid increase in hectares under maize, almost entirely hybrid, in this sector can be attributed to aggressive promotion by government extension agents and Seed Houses, the distribution of hybrid seed (and fertilisers) in free production packs, feeding of maize to people as drought relief, the ease of harvesting and processing maize in a communal setting, and the susceptibility of small grains to bird damage. Today, hybrid maize is not only the dominant crop grown in communal areas, providing the basis of household food security, the promotion of hybrid seed and recurrent droughts have almost entirely eradicated traditional varieties from the scene.

Little effort was directed by the colonial government towards the improvement of traditional small grains, which were considered to be unimportant subsistence crops. The first improved varieties of grain sorghum and millet were released in 1987. These varieties are mostly grown by commercial farmers for specialised markets such as the Stock Feeds Industry and the Breweries. The modern varieties have not been made widely available to communal farmers due to the limited amount of commercial seed being produced by the seed companies. Therefore, most of the sorghum and millet varieties currently grown in communal areas consist of low-yielding traditional varieties.

History Of Fertiliser Consumption.

...little fertiliser was used before the Second World War. Locally, only small quantities of organic fertiliser consisting of bone meal, blood meal and bat guano were available. All inorganic fertiliser had to be imported... fertiliser consumption began to rise dramatically from 1944 onwards, just prior to the introduction of hybrid maize seed (1949/50). This period, then, marked the beginning of the Green Revolution in Zimbabwe.

The most rapid growth in fertiliser consumption occurred during the nine year period from 1964 to 1974, when consumption more than doubled. In 1975 a 25.6% drop in consumption was recorded, due largely to a significant reduction in the maize hectares planted. Consumption in years 1980 and 1981 immediately following independence rose sharply largely in response to the free fertiliser (and seed) packs distributed by the new government to communal farmers. Thereafter the total amount consumed declined steadily due to the drop in numbers of commercial farms.

...prior to 1980 little fertiliser was being consumed by the communal sector. Clearly communal farmers were not able to take advantage of Green Revolution technologies at this stage. Consumption...rose sharply in 1980 and 1981 due to the distribution of free fertiliser by the government, to rise slowly over the period 1982-1986 as short term credit became more available to smallholders, and to decline from 1986 to 1990 as the Agriculture Finance Corporation tightened its credit facilities due to non-repayment of loans. Thereafter the amount of fertiliser consumed in the communal sector rose as more free fertiliser was handed out in drought-relief packs.

Even during the euphoria of the post-independence years, when free fertiliser was handed out and loans were more readily available, the communal sector appeared to be unable or reluctant to consume adequate amounts of inorganic fertiliser. The inequality of fertiliser usage...given by Humphreys (1983) for the 1982/83 season... estimates fertilizer application rates in the communal sector to be 14 kgs of nutrients per hectare compared to 177 kgs on commercial farms.

Almost all fertiliser in communal areas is applied to maize and rarely on other crops. Even then application rates are usually well below the recommended rates. Very little is applied to small grains and other basic staples...

Crop Yield History.

The changes in yield over time for maize... show very definitely that commercial farmers were able to take advantage of the Green Revolution technologies. Mean yields rose three-fold, from about 1 250 kg/ha prior to 1950 to 3 308 after 1950. By contrast...communal farmers were not able to do so. The post 1950 mean yield of 750 kg/ha is little different from the yields prior to 1950...

Comparison of the yields for sorghum from 1970 onwards... show yields of these two crops in the communal areas to be well below those on commercial farms, where very substantial increases in yields took place between 1950 and 1970 during the period when Green Revolution technologies were being introduced.

Conclusions.

The introduction of Green Revolution technologies, principally fertilisers and improved seed, brought about very substantial increases in yields in major crops in the commercial farming areas. Clearly this farming sector was able to take full advantage of the new technologies.

This was not the case in the communal sector, where crop yields stayed very much the same as they were before the Green Revolution. In addition, a marked switch in cropping strategy has taken place in this sector, with traditional small grains being replaced by maize as the basic food staple, and cash cropping coming to the fore. It is possible that these changes in cropping patterns have contributed substantially to increasing the susceptibility of smallholders to drought and making them more dependent than ever on aid.

Some of the major constraints affecting the ability of communal farmers to take advantage of Green Revolution technologies:

CONSTRAINTS IN COMMUNAL LANDS.

Prior to the Second World War, communal farming was geared towards providing sufficient food for the household. Today, under the influence of government and agro-industry extension and sales programmes, driven by the euphoric successes of Green Revolution technologies in other countries, communal farmers are growing more and more crops for sale. Today, cash is a necessity...But the real value of the change from low-input to high-input technologies can be seriously doubted if, rather than liberating, it merely entrenches poverty, food shortages and in addition undermines the self-sufficiency of farming communities.

Apart from making good sense, it is widely acknowledged that full advantage of the improved yields offered by Green Revolution technologies cannot be taken unless many important conditions are available at one and the same time. High input technologies come as a package, and any limiting factor can exercise a grave constraint on the yield-gains ultimately achieved. Yield levels, in turn, determine whether loans can be repaid and adequate levels of the new inputs purchased.

The following is a list of the main conditions which need to be present for Green Revolution technologies to "pay their way":

Adequate soil moisture. Optimal soil fertility. Uniformity of field conditions. Availability of finance. High levels of management.

Each of these will now be discussed in relation to Zimbabwe's smallholder farming areas.

Adequate Soil Moisture.

... the vast majority of communal lands fall within the semi-arid to arid zones, experiencing inadequate rainfall to support all but small areas of very drought-tolerant crops.

The rainfall pattern in Zimbabwe is mono-modal, the vast majority of the seasonal rainfall falling during the period October to April... annual amounts are extremely variable, and fears have been expressed that the variation is increasing and quantities are declining. A mid-season drought commonly occurs, which can have an adverse impact on crop production even in the more humid areas.

The data...show maize yields in the communal sector faithfully following trends in seasonal rainfall, thus substantiating that adequate rainfall/soil moisture is the factor most limiting to crop production in the drier areas of Zimbabwe.

Under the influence of high-input technologies (annual ploughing, cash cropping practices and agro-chemicals) considerable loss of valuable rainfall occurs in the form of surface runoff and evaporation. On average, 30% of the seasonal runoff is estimated to run off communal cropland during storms.

Water supplies, both surface and underground, are limited in these dryer areas and insufficient to make a substantial impact on cropping. Irrigation is limited to stream courses and wet areas in the humid areas and, in the dryer parts of the country, to the vicinity of a few irrigation schemes supplied by large dams on major rivers.

Soil moisture, probably the most important condition for successful adoption of Green Revolution technologies, is thus seriously limiting in communal areas. Lack of it can be expected to have a large adverse impact on the successful adoption of any high-input production package.

Optimal Soil Fertility.

The inherent properties of a soil play an important role in determining its response to applied fertility, moisture, amounts of inputs required and on the ultimate yield.

The majority of the soil in the smallholder sector consists of drought-prone, acid sandy soils of low inherent fertility. These soils are deficient in fine particles (clay and silt) and rely heavily for fertility (moisture and nutrient holding capacity) on the organic matter content.

The early farmers relied on shifting cultivation and minimum tillage (hoe cultivation) to maintain soil organic matter and they moved to new lands when it declined. However, rapid decline in soil fertility was noticed with the introduction of the mouldboard plough, which took place from 1920 onwards.

Under the dry conditions prevalent in Zimbabwe the organic matter is rapidly lost under annual ploughing, with most of the loss taking place within 5 years on sands and 10 years on clays. This loss of organic matter can have a major impact on rates of soil loss and runoff from arable lands.

In addition, research data from Malawi... show even modest applications of inorganic fertilisers contribute significantly to loss of soil organic matter...the experimental data also show increased applications of soluble inorganic fertilisers to contribute to soil acidification.

That too little rainfall is a severe constraint to production, particularly on the drought-prone sandy soils of the communal areas, is a matter of common sense and common experience. What is less appreciated is that loss of organic matter brings two other severe constraints in its wake. The first is that the soil can hold nutrients poorly, which wash out readily during heavy storms and restrict yields even when nutrient applications are at recommended levels. Secondly, that leaching plus removal of a wide spectrum of nutrients by each successive crop must lead eventually to the emergence of deficiencies of many of the nutrients not considered under the simplified NPK approach. In addition, a widespread feature of the sandy granitic soils of the communal areas is that, in high rainfall years or during wet periods, because of profile characteristics, they suffer regularly from waterlogging, which prevents nutrient uptake and causes further leaching losses. It is not surprising therefore that, due to the combination of these adverse forces and others, communal farmers cannot enjoy high yields even when rainfall is not limiting.

Far from enjoying optimal soil fertility, communal soils are inherently infertile, shallow, acid and prone to drought. In addition, the evidence shows that technologies associated with the Green Revolution (annual ploughing and inorganic fertilisers) are exacerbating the problem.

Uniform Field Conditions.

Successful adoption of technical packages has depended to a great extent on the uniformity of on-farm field conditions. Broad prescriptions do not perform well under variable circumstances. Green Revolution technologies, for instance, have increased yields markedly in relatively uniform (and favourable) areas of Asia and Latin America but have so far had little overall impact in Africa because of this complexity...

Smallholder field conditions are complex. Granitic soils are characterised by wide and rapid changes in texture, chemistry, and profile characteristics. It is quite common to see very marked changes in soil properties occurring even within individual smallholder fields. Textures range from fine grained sands to coarse and from clays to loams. Some sands are acid, some alkaline; some are prone to waterlogging and others are relatively well drained. Some soils are deficient in specific major and minor nutrients, while the fertility of the soil "almost next door" can be conditioned by a completely different set of nutrient deficiencies or by past practices. Packages developed at specific locations by central research organisations simply cannot cope with this degree of variability, especially when, as in Zimbabwe, most research stations were sited to serve commercial and not communal farmers.

Given such circumstances, it is difficult to imagine the simplified pattern of commercial farming being imposed upon smallholder fields.

Uniform, high quality tillage is another requirement for successful adoption of Green Revolution technologies. Since the introduction of the single furrow mouldboard plough in the early part of the century, annual ploughing has become the routine practice. Attempts to introduce Reduced, Minimum and Zero tillage techniques into the smallholder farming sector have met with very little success. The quality and timeliness of annual ploughing in the communal sector is very variable.

... studies which found that 43% of communal farmers do not own cattle and 55% have less that the 4 cattle to give adequate draught power for ploughing...a later study...covering four communal lands...74.8% of farmers were found to have less than the necessary four draught oxen. addition to having too few oxen, even after good rainfall years, the cattle are in a seriously weakened state by the end of the long dry season. The combined effect of these two factors is that most lands in communal areas are ploughed shallowly (to a depth of 150 mm instead of the recommended 230 mm) and too late in the season. The quality of ploughing in terms of spatial uniformity is also very variable.

Apart from the lack of uniformity of soil texture, fertility and ploughing quality, farm size would be another serious constraint to the adoption of the simplified, uniform, farming practices consisting of single crops spread over large areas, characteristic of fields under Green Revolution technologies. Unlike large areas, small areas cannot be easily managed or mechanised. Methods of farming have to be scaled down, operations are more difficult to perform and more labour intensive. Farming costs are generally higher that is the case with large fields under monocrops.

Thus, the lack of uniformity of soil texture, soil fertility, ploughing quality, diversity of farming and very small farm size, all militate against the adoption of the simplified, uniform, large scale farming operations which underpinned the success of the Green Revolution elsewhere in the world.

Availability of Finance.

A sound cash flow and sufficient capital are hallmarks of high-external-input technologies. Smallholder farmers do not earn sufficient to purchase the inputs and have unsteady cash flows.

... in 1985 Norad estimated the cash income to be less than $720/yr made up as follows: 40% from agriculture;30% from cash transfers from town;30% other employment & non-agricultural activities.

Farmers are reported to be applying considerably less than the officially recommended fertiliser rates because they cannot afford to do so or in order to reduce the risk of financial loss should the crop fail. Page and Chonyera (1994), for example, found that 64% of the farmers in their sample had applied less than the recommended amounts of fertiliser. It appears that the majority of the farmers have found low-external-input strategies more cost-effective...

In their economic study of maize grown during the 1990/91 season which was carried out in a year of reasonable rainfall (national average 502 mm compared to 335 mm in 1991/92) in four top maize producing communal areas... Chiweshe, Page and Chonyera (1994) found that among the 32% of the farmers who had applied all the officially recommended fertiliser to their maize crop, often by obtaining these inputs on credit, yields were so low that 48% of them could not have met the grain needs of their families and had sufficient maize grain left for sale to cover their loans.

The fact that nearly half of the farmers using the high-external-input approach cannot make ends meet is mute testimony to the lack of appropriateness of these Green- Revolution-style packages under smallholder conditions.

The financial position of farmers could be improved if increases in producer prices were to exceed the rising costs of fertiliser... in general, increases in producer prices lag well behind the rising costs of fertiliser... fertiliser cost 35% more than the list price by the time it gets onto the farm.

Clearly, under smallholder conditions, income from cropping in general is insufficient to pay its way and has to be subsidised by other on-farm and off-farm income-generating activities. Access to credit provides no relief under such circumstances as, even when recommended fertiliser rates are applied, yields from Green Revolution crops such as maize are too low to enable loans to be repaid. Most farmers, it appears, are driven by high risk factors to minimise costly external inputs.

The fact that producer prices are not keeping pace with the cost of fertilisers has inhibited past usage and bodes ill for the future, especially since fertiliser purchases generally account for 60% of input costs...

High Levels of Management.

High levels of management are essential to the success of high input technologies. Among those factors found most vital under local conditions are: appropriate crop varieties, optimal fertilisation, timeliness of planting, weed control and pest control. Adequate training of farmers needs to be supplied before they can adopt new strategies, particularly those requiring high standard of management.

1. Appropriate Crop Varieties.

Generally, understanding of the importance of matching crop variety with field conditions is poor among both smallholder farmers and their advisers. It seems obvious that there is little point in planting a high-yielding variety on a farm which does not enjoy the optimal soil, rainfall, fertility and management that will enable the yield potential to be realised. But this is precisely the case in the smallholder sector of Zimbabwe. Hybrid maize varieties are distributed throughout all the regions of the country in spite of the low yields attained...

In spite of the fact that Natural Region IV and V are classified as unsuitable for cropping, maize has been promoted throughout these areas via the post-independent free packs and drought relief measures. Though the people once preferred the taste of small grains they now prefer maize through being supplied with maize meal as drought relief food. Furthermore, drought relief production packs commonly contain a high proportion of maize seed for planting. In 1992 even the long season variety SR52 was supplied to Natural Regions IV and V for planting the following season. In addition, in 1995 the seed in these packs was predominantly hybrid maize (70% maize and 30% small grains). As discussed earlier these regions typically experience a drought at least one year in five (seven years in twelve being the highest reported in this paper). Naturally these drought relief policies have ensured that people will continue to plant maize in unsuitable areas and will inevitably become more and more dependent upon aid...

Except in the few optimal conditions existing in communal areas (fertile soils, adequate rainfall and/or irrigation, adequate cash and good management), there is little justification in persuading farmers to plant hybrid maize with a potential of 6-8 t/ha when the actual yields obtained are of the order of 1 t/ha. Open pollinated varieties with yield potentials of 3t/ha or more are more appropriate for general conditions and will save farmers the cost of buying seed.

Small grains are the most appropriate crops for many of the drier communal lands. Before the colonial era and for a period afterward, sorghum and millet formed a substantial part of food security. For years, these important subsistence crops were ignored by research and extension. A limited amount of research was conducted on them prior to 1950 but the results were disappointing. The first improved varieties of grain sorghum and millet were released as late as 1987 but have not become available to communal farmers due to commercial seed supplies not being made available. The situation today is that the majority of farmers in the marginal rainfall areas are short of small grain seed due to the combination of successive droughts, the aggressive promotion of maize (contrasting starkly with the scornful attitude of farm advisors to small grains) and the shortage of replacement seed.

The above considerations show that, as far as the most important crop, maize, was concerned potential production gains were frustrated by the promotion of maize per se into inappropriate climatic areas and by the promotion of inappropriate high-yielding varieties (hybrid) into the generally low fertility conditions in the smallholder sector. As far as the two next most important smallholder crops are concerned, millets and sorghum, potential production gains were frustrated by the lack of attention paid to the crops by research and extension, shortage of seed and the failure to make improved varieties available to smallholder farmers.

The conclusion of this section is therefore that the important condition that "appropriate crop varieties should be available" as part of the Green Revolution package has not been met. Without doubt this has had a significant and adverse impact on attempts to introduce high-external-input packages into the smallholder sector.

2. Optimal Fertilisation & Timeliness of Planting.

As described in earlier sections the majority of smallholder farmers do not apply the recommended rates of fertilisation, but opt for lower yields through adopting low-input strategies. Manure is the most common source of on-farm fertility used by smallholders. However, supplies of manure are limited as most householders do not own cattle or have too few cattle to provide sufficient manure. Where manure is in short supply, anthill and leaf mould are commonly used.

It appears ...that in opting for lower input combinations of fertiliser and on-farm organic amendments, smallholders who are able to afford some fertiliser manage to achieve yield levels in keeping with the level of fertility they apply to their fields. Mixtures of organic and inorganic fertilisers are likely to be more sustainable in the long run than reliance wholly on inorganic fertilisers which, as discussed in an earlier section, leaves the soil prone to loss of organic matter, acidification, micro-nutrient deficiencies and soil erosion and high runoff.

Timeliness of planting is important if optimal yield levels are to be obtained. Early root establishment increases effective season length...and...effective season length and quality of the rainfall season are by far the most important constraints to economic dryland crop production. Early planting also acts as a buffer against the mid-season drought. In ...,drought years (1991/92 & 1994/95), early-planted crops were observed to fare better than late planted crops in almost all areas.

Small-scale farmers are rarely able to achieve timely planting. Arising from the weakened state of draught oxen by the end of the dry season and the hard nature of the dry soil, farmers have traditionally ploughed their fields with the first soaking rains and planted later. As a result even farmers owning 4 draught oxen cannot achieve the optimal planting date i.e. plant with the first rain. Farmers having no oxen plant even later, for they have to wait for the fields of the oxen-owners to be ploughed first. Another delaying factor is that smallholders plant by hand, a laborious process taking time. Sandy soils can hold only a limited amount of moisture that rapidly evaporates in the hot sun. A delay of one day in planting can make a considerable difference to crop yield. Thus only a limited area can be planted during the period when moisture is optimal.

... many farmers, because of the remoteness of the areas and supply and transport difficulties, experience problems in obtaining their inputs in time to meet the optimal planting dates.

The success of Green Revolution high-external-input packages depend to a large extent upon optimal fertilisation and timeliness of planting. Neither of these essential factors are within the grasp of most smallholder farmers.

3. Weed and pest control.

Weed control is vital to crop production. Under Zimbabwe's conditions the presence of weeds can completely nullify yields or reduce them significantly. An experiment into weed biomass on different peasant tillage systems Vogel (1994) found the crop (maize) to face such aggressive weed competition that crop establishment was threatened when weeding was delayed by 20 days.

The poor resource base and meagre crop yields of communal farmers renders most chemical and mechanical control methods unfeasible. Hoe weeding is the most common method of weed control in the smallholder sector. This method is highly labour intensive. Labour is generally insufficient to allow more than small areas to be weeded clean or timely.... Yield losses and even total crop failure are often due to inadequate weeding.

Smallholder crops are subject to attack by numerous pests... an experiment showed the decline in yields of well-fertilised continuous maize to be largely due to soil pests. Crop rotations have been advocated to control pests in the absence of agro-chemicals... However, crop rotations have been pushed out by the simplified monocropping advocated by followers of Green Revolution technologies.

Unlike the weed and pest free fields envisaged by the developers of high-external-input packages, smallholder farmers do not have the finances to purchase the necessary chemicals nor the spray equipment to apply them. Labour is insufficient to keep pace with weed infestations and the extension services have little to offer in the place of agro-chemicals for pest control.

4. Adequate Farmer Training.

...the wide range of technical expertise in the small-scale farming sector has long been recognised.
Apart from the training component, the major distinction between Master Farmers (smallholders and small-scale commercial farmers trained to apply high-external-input packages) and Non-Master Farmers is their respective resource endowment. Non-Master Farmers have less draught power, fewer farm implements, less finance to purchase inputs and lower access to information... Of this situation, Martin Whiteside comments:

"Many agricultural programmes have not taken sufficient notice of the diversity among farmers. Worse still, agricultural policy, research and extension have often been directed at an unrepresentative sector of farmers atypically richer, male, and less remote."

Thus, it would appear that only the minority with sufficient resources to be able to apply the costly technologies receive training. This may make good sense, but adds yet another explanation to reasons why the majority of smallholders have been unable to take advantage of the Green Revolution technologies. It would seem that, far from bettering the lot of the resource poor, the countrywide extension focus on high-external-input technologies has contributed substantially to undermining the household food security and incomes of the rural poor.

CONCLUSIONS.

The introduction of Green Revolution into Third World countries made headlines during the years following the Second World War. Politicians, scientists and sales representatives paid homage to the technology in glowing terms. The new technologies began to be introduced into Zimbabwe in the fifties. Releases of new maize hybrids coincided with rapid increases in the use of inorganic fertiliser. Although the commercial sector was able to benefit in terms of increased yield and cost-effectiveness, the vast majority of smallholders were unable to do so.

Compared to the low input strategies of post Green Revolution days, average yields in the smallholder sector have not generally improved at all. In the wake of the rapid spread of these technologies into the more marginal rainfall areas during the years following independence, the food security and economic viability of smallholder farming has deteriorated further. Most households eke out a mere survival by non-agricultural income generating activities.

It would seem that, far from bettering the lot of the resource poor, the countrywide extension-focus on high-external-input technologies has contributed substantially to undermining the household food security and incomes of the rural poor.

Attempts have been made to offset the deficiencies in the high-external-input philosophy by showing that lower levels of the same inputs would be more practical...but perhaps the philosophy itself needs to be seriously challenged.

It has been shown that successful adoption of high-external-input technologies requires the concurrent presence of many supporting conditions. The technology simply does not work, cannot pay for itself, if these conditions are not present. The information in this paper shows that all the most essential conditions are absent from the communal smallholder sector or are inadequate to meet the requirements for successful adoption of high-external-input technologies.

A question relevant to our times is: "should the traditionally diverse, complex and dynamic way of life of smallholder farmers be changed taking into account the conditions of smallholder farmers described in this paper?"

That very complexity, diversity and ability to respond rapidly to changes in the environment, to market forces and to personal circumstances, are the characteristics that allow farmers to survive in harsh conditions. The simplified high-input style of farming advocated by proponents of Green Revolution technologies are seriously jeopardising the ability of these farmers to survive.

The new Ecologically based movements arising in Africa and around the globe are offering sounder, more practical and environmentally safer approaches for achieving future production goals, and do not inhibit the dynamism of traditional practices. For these to bear fruit, however, the aim of production itself needs to be reviewed.

The justification for the Green Revolution was "more food to feed the expanding populations of the world" but, perhaps the understanding that "less food produced does not necessarily mean more people will be hungry" would have modified the excesses that followed. Recent events have shown that more food does not necessarily mean a reduction in world hunger. Poor distribution facilities, politics, corruption and hard economics have ensured that food does not get to hungry people in enough quantities nor in time.

Agriculture of the future should not aim at simple maximisation of production in some parts of the world in order to feed other parts, but at ensuring that every rural household can produce sufficient food for its own needs, plus a little left over for sale. A world in which most farmers depend on food handouts and financial aid in order to survive is clearly not the answer to our problems. Yet this is precisely the situation perpetuated by so-called Green Revolution technologies and accompanying philosophies.

*The study was done in 1999, just before wholesale changes in Zimbabwe's land-holding patterns, and declines in all sectors of agriculture. This abbreviated version omits the references, diagrams and bibliography of the original.

New nitrogen-fixing soil fertility method boosts crop production in Kenya

by Bob Koigi

An innovative method of boosting soil fertility has increased yields for farmers in Western Kenya by up to 10 times, promising to increase harvests and boost nutrition if adopted on wide scale.

The four-year project, which was launched last year, has raised the net returns for farmers who adopted the legume and rhizobial inoculant technologies.

Launched in Kenya and seven other African countries to triple the take-up of free atmospheric nitrogen through Biological Nitrogen Fixation, the project has delivered near-instant benefits through improved crop and livestock productivity, nutrition, farm income and soil health.

It has also sparked a revolution in legume processing, specifically of soya, in Western Kenya.

The project’s total benefits at the end of the four years are projected to be at least $31.9 million based on estimates of the increased productivity of the targeted grain legumes— which include soya-bean, common beans, cowpeas, groundnuts, chickpeas and pigeon peas — and through their contribution to the yield of subsequent maize crops.

However, in Western Kenya where around 20,000 smallholder farmers from more than 10 districts were targeted, they have already increased their net returns from soya-bean cultivation from four to 14 times.

The initiative has also led to the creation of several soya-bean resource centres in Western Province, with many farm families now easily accessing soya-milk, and farmers widely adopting soya-milk processing machines.

Agriculture experts say the legume crops often fail to fix useful amounts of nitrogen in the soil in Africa because partner bacteria are not present, or because the soil lacks other nutrients, such as phosphorous.

But the new technology now allows farmers to introduce the bacteria as inoculants, together with the seed and small amounts of other nutrients.

This simple package increases farmers’ yields while improving the soil’s fertility.

“Agricultural production in most parts of sub-Saharan Africa is dominated by smallholder farming systems, which are associated with low productivity. Although the inclusion of legumes has the potential to improve system productivity, often less than five to 10 per cent of cultivated land is currently planted with field legumes.

Grain legumes are often included as minor intercrops in fields of cereals and other staple crops.

This is because smallholder farmers operate under diverse socio-ecological constraints that limit the productivity of legumes and farmers ability to scale up the integration of legumes into their farming systems,” said Wycliffe Oparanya, Minister of State for Planning, National Development and Vision 2030 during the launch of the Biological Nitrogen Fixation project last year.

Despite an Africa Union resolution in 2006 when leaders endorsed efforts to improve fertiliser access for small-scale farmers, by promoting locally-adapted manufacturing and establishing financing mechanisms for procurement, smallholders are still struggling to access the input.

Agro-experts have therefore become aggressive in pushing biological nitrogen fixation, which is sometimes free and is easy to learn, as the best route to follow for Africa.

The process involves crop rotation, with the planting of legumes helping to fix nitrogen naturally.

According to Kenya Agricultural Research Institute, the country faces an enormous soil fertility problem, with research showing that in Western and Central provinces, 7.5 million hectares of land are highly acidic, a problem shared by large parts of Ethiopia, Rwanda, Uganda and Zambia.

The high acidity is due to the leaching of nutrients by the abundant rains, continuous cultivation and misapplication of nitrogen fertilisers.

However, in Brazil and South Africa, agricultural scientists have manipulated the symbiotic relationship between the growth of legumes.

Business Daily Africa

Bean crops may cut fertilizer use, subsidy costs

by Steve Baragona

A new study finds that governments can reduce the amount they spend on fertilizer subsidies - and free up resources for health, education or other priorities - by encouraging farmers to alternate maize with certain bean crops.

Scientists in the chronically-malnourished African nation of Malawi developed farming methods that produce the same yields using just half the fertilizer - a big potential saving for the Malawi government, and a potential model for other developing-countries.

But critics say poor farmers would do better right now using more synthetic fertilizer, not less.

In recent years, Malawi has taken major steps to increase its faltering food production by making synthetic fertilizer and high-yielding maize seed available to farmers at a steep discount. Nationwide, the program has been credited with increasing maize production by up to 30 percent.

But the costs of the project consume about one-sixth of Malawi's national budget.

"There's a lot of concern by the Malawi government in what is the sustainability of this," says Michigan State University crop scientist Sieg Snapp, "because if you invest in fertilizer, then there is less ability to invest in education and roads, other things. Obviously, there are tradeoffs."

Snapp and her colleagues wanted to see if farmers and governments could get more value from their fertilizer investments by adding bean crops known as legumes to the planting schedule.

Farmers have long known that legumes naturally fertilize the soil with the nitrogen they produce. But they have also known that legumes typically don't provide the kind of productivity boost possible with synthetic fertilizer.

Snapp's research focused on a different kind of legumes: shrubby legumes like pigeon pea and mucuna that mature more slowly than other legumes. That means they spend more time in the ground producing nitrogen fertilizer. And the ground stays covered with living plants for longer -- another benefit for the soil.

So when farmers grow maize the next year and add the normal amount of synthetic fertilizer, the soil is rich and ready. In the study published in The Proceedings of the National Academy of Sciences, Snapp says the maize-and-shrubby-legume rotation produced as much grain as growing maize with synthetic fertilizers both years.

"We're producing the same amount of grain," she says, "but...at half the amount of fertilizer."

Spending less on fertilizer helped make the shrubby legume rotation three to four times more profitable, which Snapp says is critical if farmers are going to change their practices. Plus, she adds, yields from the shrubby legume rotation were more reliable year after year.

"A lot of people just focus on the production," she says. "But if it isn't stable, it isn't every year you can count on that, that puts your country at risk."

Snapp says the shrubby legume rotation can reduce the risk of food shortages at lower cost -- to farmers and national governments -- than expensive synthetic fertilizers.

Glenn Denning is a specialist in agriculture and food security at Columbia University's Earth Institute. He agrees that legumes serve important functions improving the soil and providing a source of protein.

"But I don't think this is the right time to de-emphasize fertilizer use in Malawi, or anywhere else in Africa, for that matter," he says.

Denning says even with the subsidy-driven increase in fertilizer, maize yields in Malawi are still far below what they could be. And he says farmers could apply twice the fertilizer used in Snapp's study and increase their yields more than they could with legumes.

That would free up land for other crops. "And in that way," he adds, "small-scale farmers, instead of devoting their whole land area to maize simply so they've got enough to survive on, they could devote half or two-thirds of their land to maize and the rest they could put into other crops, including legumes."

Denning notes that pigeon peas are an important part of the cropping system in a major project he works on in Malawi. He says they do have potential in the government's subsidy program.

"I think you could cut your costs in some places where these legumes will really make a difference." But, he adds, "I think the jury would still be out as to how widespread you could effectively introduce those legume rotation systems at this time."

Current pigeon pea varieties do not grow well in many parts of the country, he says.

Denning expects legumes will play a bigger role in fertilizer subsidy programs. But he says they should complement, not replace, synthetic fertilizers.

VOA