Progress in the utilization of urea-ammonia treated crop residues: biological and socio-economic aspects of animal production and application of the technology on small farms
Revised version of invited paper presented at the 29th annual meeting of the Brasilian Society of Animal Production, Lavras, July 20 - 24, 1992.
University of Arhus, 8000 Arhus C, Denmark.
Treatment of fibrous crop residues using urea as a source of ammonia is a technology easily handled by small farmers. However, adoption of the technology has been slow, except in China. In the first part of this paper the conditions for biologically efficient results in terms of animal production are discussed. Drawing on experiences from mainly two countries (China and Bangladesh), important conditions for farmer uptake including socio-economic factors are discussed in the second part. Within the framework of the paper they are found to be land tenure, rural energy supply and the political and administrative situation. It is concluded that a strong farmer's perspective in both the research and extension phases facilitates successful adoption. The discussion also implies that secure land tenure rights are an important condition for uptake of technologies by smallholder farmers.
KEY WORDS: Smallholder farmers, crop byproducts, ammonia treatment, urea, supplementation, on-farm trials, adoption of technology.
Treatment of crop residues with ammonia using fertilizer grade urea has received much attention, especially in Asia in recent years after it was established in Bangladesh, about a decade ago (Dolberg et al 1981), that the method could be applied on small scale farms. However, farmer adoption has been much less than initially expected. As recently as October 1991, one of Asia's leading animal scientists (C Devendra, personal communication) pointed out that 28 meetings on straw utilization had been held in Asia the past 17 years and yet farmers were disinclined to use the technology.
Recent progress in adoption of the technology in China has, however, been encouraging and it is against this background that this article is written, the major objective being to identify and discuss the non-technical factors of importance for adoption.
In the first part of this paper the results of research concerning key aspects of the technology will be discussed. In the second part the focus will be on socio-economic factors of relevance for implementation.
Treatment of roughage of low digestibility
Ammonia (urea) treatment
Of the available chemical treatment techniques, ammonia (urea) treatment (Sundstol and Owen 1984) has the most practical relevance to small scale farmers. It was the promises contained in this possibility which caused a flurry of research activities on treatment of crop residues in developing countries (Doyle et al 1986).
Urea (5% urea measured on air-dry straw) is dissolved in water and sprinkled on layers of straw. The quantity of water may range from 0.3 to 1 litres of water per 1 kg air-dry straw with a minimum being applied in areas with water scarcity. In the event that freshly harvested straw contains much green material or has recently been exposed to rain, then the urea can be applied without being dissolved in water. It is implied that this method can be used to preserve wet straw, although this feature of the technology has not received much research attention.
Container and cover
The treated straw can be stored in various ways. However, airtight storage produces the best result (Ibrahim et al 1984). The data in Table 1 demonstrates that the difference in digestible dry matter intake due to type of container and/or cover can be as high as 41%.
|Table 1: Dry matter (DM) digestibility and digestible DM intake of urea-ammonia treated rice straw stored in three different ways|
|DM intake (g/kg LW/d)||24.3||28.6||29.8|
|DM digestibility (%)||53.0||59.5||61.1|
|intake (g/kg LW/d)||12.9||17.9||18.2|
Source: Ibrahim et al 1984
The airtight condition is easily achieved by applying a plastic cover. A concrete pit, placed above ground, lined with plastic will invariably produce a good result. But both concrete, bricks and plastic can be difficult to obtain for reasons of cost or availability. Alternatives can be worked out locally. In dry areas, they can be pits in the ground lined with straw, banana or bamboo leaves. In areas with more rain, they can be stacks up against a wall or - as is seen in India - fine meshed wire such as chicken wire, used to contain the straw. When straw is stacked against firm structures (walls, inside pits, meshed wire), trampling can be done and compact, wet straw will not allow air to enter.
Treatment time may vary from one to four weeks. In the intensive work undertaken in Bangladesh and Sri Lanka in the early 1980s, seven to ten days were normally used with no benefits in animal performance obtained by treating for a longer duration (Perdok et al 1984). However, temperature and treatment time are inversely correlated and more time is required in the winter or in a colder climate. In well-compacted straw the temperature rises, the extent being subject to quantity of straw and temperature, but already by the second day it may be five celsius degrees and on day seven as much as ten degrees above ambient temperature (Saadullah et al 1981). The specific, practical method of treatment is best worked out locally within the guidelines outlined above. Simple tests of successful treatment are: a browning in the colour of the straw, a strong smell of ammonia and absence of rotten and moulded straw.
Type of material
All types of cereal straws can be treated. Rice straw can be treated in a long form, but it may be necessary to chop stiff- stemmed straws such as wheat in order to obtain a sufficiently compact condition of the material during treatment. Relatively speaking, the greatest treatment effect is obtained with the poorest material.
Feeding ammoniated straw
The entry point - type of animal
There has to be a good economic reason for a farmer to feed treated straw -and the effect has to be visible. For these reasons straw treatment has been most successfully taken up when fed to crossbred milking cows or used in beef fattening programmes. A feasible rationale for feeding limited quantities of treated straw to working animals has only recently become an option based on work in Thailand (Wanapat 1991) in which it was demonstrated that during the four-month dry season feeding working animals a small, fixed amount in the morning before grazing, led to improved work by the animals and a higher sale price after the ploughing season was over. This research demonstrates the importance of both research and extension being problem-led - a point that has been absent in much straw research work so far.
When animals are fed ammoniated straw ad libitum, they will typically increase their dry matter intake by 30% or more (Han and Garrett 1986).
Supplementation with protein
Ammoniation alone will lead to some increase in production, but the full potential will only be realized when the correct supplements are added. A supplement of bypass protein is the most important. This was dramatically illustrated in Bangladesh, when 50 g/d of fish meal added to a basal diet of ammoniated rice straw more than doubled daily liveweight gain of growing cattle and a significant response was obtained to as little as 15 g/d (Saadullah 1984). Work from many parts of the World (Preston and Leng 1987; and more recently in a UNDP/FAO project in China) has demonstrated that for practical purposes, very economical responses are obtained to 1 kg/d of cottonseed cake or similar, more conventional sources of protein. A one hundred to one hundred and fifty percent increase in daily liveweight gain has been quite common, with this level and type of supplement but with much smaller responses to further increments.
|Table 2: Response to small quantities of fish meal by cattle fed urea-ammonia treated straw ad libitum|
Mil powder (g/d)
Source: Saadullah 1984
Supplementation is expected to correct any imbalances in the nutrients presented for metabolism. It is well established that ruminants fed low-N roughages respond to a source of protein (Orskov 1982: Preston and Leng 1987). However, it is often assumed that such protein should remain relatively undegraded in the rumen. In the example being discussed (Table 2), the fishmeal was sundried and therefore the protein was relatively soluble and the effect was probably at both rumen and post-rumen level (Saadullah 1984), since digestion of the basal diet was increased by approximately five percentage units. A protein source which is highly soluble (milk powder) did not improve animal performance. Although, the author was not able to explain these effects (Saadullah 1984) it was clearly demonstrated the potential for enhanced roughage utilization, provided a functional rumen environment is created by correct supplementation and additional amino acids are supplied in the form of protein which escapes (partially) the rumen.
Much recent work with the urea-molasses block (Habib et al 1991, Hendratno et al 1991; Saadullah 1991) appears to point in the same direction. Merry et al (1990) found in their work on the effect of nitrogen source on rumen microbial growth and fibre digestion that fish meal increased the extent of digestion of cellulose, glucose and arabinose (the last derived from the hemicellulose fraction). However, they concluded that "the most desirable characteristics to look for in dietary protein sources are poorly understood".
A supplement of green legume forage, obtained from shrubs, tree leaves or water plants may further enhance the utilization of the straw by ruminants, although the need seems to be smaller for animals fed treated straw (Orskov and Ryle 1990). This has been demonstrated by several workers (Preston and Leng 1987) and recently in China with both treated and untreated straw as basal diets (Feng Yu 1991). It is now becoming a focal point of research attention, often in combination with studies on the role of phenolics. Data presented by Reed et al (1990) indicate both the variation in responses that can be expected to supplements of tree leaves and the promise contained in the approach.
|Table 3: Intake and growth rate for sheep consuming untreated teff straw as basal diet in combination with either tree leaves or urea|
|Intake (g DM/day)|
|Liveweight gain (g/d)||-11||48||10|
Source: Reed et al 1990
The results reported in Table 3 indicate that although supplementation with trees and legume shrubs is an attractive possibility from a local resource utilization perspective, animal performance can vary so much in response to these supplements that some caution (as a minimum a pilot trial should be conducted in each location, before recommendations are made for large scale application) in recommendations to farmers is needed till the required research has been conducted and made the outcome of any recommendations more predictable. Rather than total replacement, it may be more realistic to go for partial substitution. Thus Pezo et al (1989) present data from a trial in which it was found that replacing 67% of a soybean meal supplement with the foliage of a legume tree (Erythrina poeppigiana) reduced daily gain by 11% in dairy heifers (from 410 to 366 g/d). However, at 100% substitution, daily gain was reduced to 294 g/d or by 27%.
This brief discussion of the effects of protein and green forage supplements lead to the conclusion that there are two areas in which further work seems highly justified. One is to identify the precise mechanism of the responses at rumen level to supplementation with true protein of different degrees of solubility; and the other is identification of a variety of locally available sources of protein supplements, which need to be evaluated to enable prediction of animal responses. For reliable extension work, the last point is extremely important.
Treated straw as a supplement
Recently, it has been demonstrated that ammoniated straw can be used as a supplement, which will promote increased intake of untreated straw (E R Orskov, personnel communication) due apparently to an increase in the population and/or activity of rumen bacteria digesting cellulose in a manner similar to some legume forages as discussed above. A 20 to 40% supplementation with treated straw led to an increase in total straw intake by approximately 40%.
Starch and sugar
It is well established that supplements containing starch and sugar (cereal brans and molasses) must only be added in very small quantities to basal diets of fibrous roughages as too much (beyond 15 - 20 % of the total diet) will tend to depress the digestion of the basal diet, resulting in inefficiency in feed utilization (Orskov and Ryle 1990).
Size of digestive system
Work first undertaken by Mould et al (1982) in Bangladesh indicated that the relative size of the digestive system in ruminants may influence their ability to utilize roughages of low digestibility. This has subsequently been confirmed in Friesian cattle in Scotland (Orskov and Ryle 1990).
Differences in feeding value of straw fractions and varieties
A sufficient amount of work has by now demonstrated that large enough differences exist between straw fractions and varieties, which will justify further work in this area (Flachowsky et al 1991) in order - via plant breeding - to provide for both food (grain) and feed (straw). In cases where it is needed for both fuel and feed, it may be fractionated as the leaves are having higher feeding value than the stems and they are more palatable. This holds in all cases except for rice straw, where the stem has a higher digestibility than the leaves. Yet the leaves are more palatable and therefore eaten in greater quantity (E Owen, personal communication). A similar situation holds in the case of the banana pseudo stem and the leaves. The stem is more digestible than the leaves but intake of the leaves is higher (Ffoulkes and Preston 1978), probably because the leaves contain more protein and other essential nutrients. Thus balance of nutrients is more important than digestibility, as a determinant of animal performance, since digestibility only indicates the potential value of a feed.
Voluntary intake, daily liveweight change, milk yields, responses to increasing levels (response curves) of supplementation, crude protein content and nylon bag degradability of dry matter and protein are the parameters, which it has been useful to study to arrive at the present level of understanding of the utilization of roughages of low digestibility. Traditional chemical analyses have contributed very little (Orskov and Ryle 1990). In contrast, observations and trials on farms have made a major contribution (Dolberg and Sriskandarajah 1989). The greater palatability of the rice straw leaves in comparison to the stems is an excellent and up to date illustration in support of the statement, which by some may be considered "sweeping". Accepting, the almost complete inability of chemical analysis to predict animal performance on low quality roughages, workers at the Rowett Research Institute had found a very strong, positive correlation between rate of dry matter degradation as measured by the nylon bag technique and intake (Orskov and Ryle 1990) and therefore considered this a more valid evaluation technique. The approach applied to rice straw indicates that animals would eat more of stems than leaves. However, given the choice, animals preferentially eat leaves (Orskov and Owen, personnel communication), bringing the validity of what was considered an improved system into question, but supporting the need for very basic observations like animal intake.
Case study: treatment of crop residues. Success in china and failure in bangladesh. Attempt at finding the reasons
The early technological breakthrough took place in Bangladesh (Dolberg et al 1981), but farmer adoption was disappointing, notably among farmers who had readily accepted other new technologies like fresh water fish culture (Dolberg 1991).
There has been a strong interest in treatment of crop residues in China in recent years because: use of crop residues for animal production can save grain, provide additional income to farmers and environmentally, it is a constructive way of avoiding the pollution, which follows post harvest straw burning. According to information provided by the Ministry of Agriculture, the following quantities (Table 4) have been treated since 1985. As can be seen adoption is moving fast with an estimated 4 million tonnes treated in 1991.
|Table 4: Straw treated in China (million tonnes)|
Source: Ministry of Agriculture, Government of the People's Republic of China.
Factors contributing to uptake in China
Use of the appropriate ammoniation technology is important. Comparisons of figures for quantities treated in 1990 and 1991 (Table 5) by either anhydrous ammonia (centralized supply and inflexible response to farmer needs) or urea (decentralized and flexible supply via the market) demonstrate this in an ongoing FAO/UNDP sponsored project, which was preceded by two FAO/TCP projects.
Of four project areas (counties), two were originally set to use anhydrous ammonia and two urea. However, in 1991 farmers in one of the anhydrous ammonia counties got the choice between urea and anhydrous ammonia treatment. The result is that practically all farmers have shifted to urea as a source of ammonia and the quantity of straw treated has doubled from 5500 tonnes in 1990 to 11000 tonnes in 1991. This is in contrast to the other project county giving priority to anhydrous ammonia, where the increase has only been 16%, but from a low level of 5000 t.
In the project areas, cotton cultivation is common and cottonseed cake is easily available and cheap. The price is only about US$ 83/tonne, which is less than half the price farmers in Denmark have to pay (US$ 194/tonne). However, straw, urea and protein supplements are also available in Bangladesh but here was no farmer uptake. It is therefore necessary to probe deeper to find the answer to adoption in China. It is suggested that the reason lies in different socio-economic factors, although the following discussion should not be taken as the final answer.
|Table 5: Comparison of quantities (thousand tonnes) of straw treated in four countrys by year and method of treatment.|
* NH3 in 1990; urea in 1991
Source: Dolberg 1992
Availability of straw: the national and the farmer's perspective
Whether it is in China or Bangladesh, from a national perspective, there is plenty of straw in both countries compared to other feed resources. The difference between the two countries does not become apparent till an individual farmer's perspective is applied. Skewed landownership with many farmers having less than half an acre or no land at all means that the majority of farmers in Bangladesh have very little or no straw and if they have to buy, they have to pay a high price. Straw is used as fuel and working bullocks do surprisingly well on untreated, but supplemented straw (Barton 1987). Although there is some indication that multipurpose working and milking cows benefit from a feed of treated straw (Barton 1987; Saadullah 1991) they are kept by farmers with the smallest landholding, having little or no straw. Small farmers get access to more land through sharecropping, i.e. by hiring land, paying all cost of production and sharing the harvest with the owner. It is a system, which does not encourage high crop yields, because they will demand investments in fertilizers, seeds etc. - an investment from which the cultivator will not reap the financial benefit. In contrast, access to land in Chinese villages is much more equitable and cultivation extremely intensive, providing an abundance of residues on the farms with no alternative use as coal is used as fuel and tractors do the work, leaving plenty of straw on each farm available as a feed for ruminants.
According to the author's interviews with hundreds of small farmers in Asia and Latin America, insecure land tenure rights is a problem in the way of increasing small farmer production in several countries. And it is unlikely farmers will undertake any major investments unless they are certain they will also get the benefits of such investments.
|Table 6: Straw utilization factors in China and Bangladesh|
|Access to land||Even||Uneven|
|Price of straw||low||high|
|Straw used as fuel||No||Yes|
|Political and adm. support||Yes||No|
|Training of scientists||No||Yes|
|conducive to technical assistance||Yes||No|
Resources and decision-making power
Feed resources and capacity to make decisions are present on the same farm in China, but this may not always be the case in Bangladesh. Although there are differences in farm sizes in Chinese villages, there are no absentee landlords. There are comparatively large farms in Bangladesh, which do not venture into intensification through animal production, because it requires a higher degree of day-to-day management than an absentee landlord can provide or he feels time and money is better invested elsewhere. So, while the small farms may have insufficient feed resources the large farms with sufficient crop residues may have a management constraint.
Support from the top
In China, compared to Bangladesh, there is a strong administrative and political support to the introduction of the technology.
In Bangladesh, there are certainly scientists who have a good understanding of the technology and the principles involved. Dr. M. Saadullah's contribution is internationally acknowledged. Some NGOs are making important contributions such as the Bangladesh Rural Advancement Committee and the Mennonites Central Committee. The newly established Livestock Research Institute (World Bank loan and international technical assistance including FAO/UNDP) has not yet made any significant contribution, although the scientists are familiar with the technology. The importance of the local agro- ecological and socio-economic factors are put into perspective by the fact that, when they are conducive, international technical assistance can be effective and much less so, when they are not. FAO/TCP and FAO/UNDP have been involved in introducing the ammoniation technology to China, where it is being adopted on a large scale, but they also have had projects in many other countries where it has not moved beyond the pilot phase. A critical point in China is now to establish a closer link between the scientists and the farmers in order that scientists may address technical bottlenecks, which may be caused by the rapid adoption and which are researchable.
A summary of the position concerning the different factors discussed is provided in Table 6.
Conclusion and direction of future research
This brief discussion of biological factors such as ammoniation, protein and forage supplementation, selection of straw varieties and attention to the animal characteristics, indicates that sufficiently focused research incorporating all these aspects will make it possible to develop productive livestock feeding systems using the so -called "low-quality" roughages as the basis of the diet. In the meantime, so much is now known about the practical possibilities for application of the technology that it seems justified to go ahead with implementation.
In this latter context, it is relevant to pay attention to important conditions for application of the technology under small farmer conditions, which - according to the examples from China and Bangladesh - need to comprise both biological and socio-economic factors.
Concerning availability of straw, it is the farmer's perspective, which needs to be applied. It includes factors such as size of farm, present straw use and possible alternatives, season, cropping pattern and type of animal production (work, milk, fattening, dry season feeding and growth). It is particularly important to find out, whether - from the farmer's perspective -straw is plentiful or scarce. However, before small-scale farmers will be prepared to invest in new technologies, in many countries they have to be assured of their rights to the land they cultivate.
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(Received 1 August 1992)