Livestock Research for Rural Development

1997, Volume 9, Number 5

Urea treatment of straw: a farmer - friendly system improved upon in Balochistan

 

P B O'Donovan, F M Soomro, J P Wagenaar, Shafiq-ur-Rehman and Farhat Abbas Bukhari

Livestock and Dairy Development Department, Government of Balochistan, Pakistan
(Project PAK/88/050)

Abstract

Wheat straw provides in excess of 80% of the winter roughage for small ruminants (sheep and goats) in Balochistan province in Pakistan. This article addresses some of the issues that relate to upgrading of straw with urea and describes low-cost, practical and "farmer - friendly" ways by which this technology can be adapted to the needs of poor smallholder farmers. Emphasis is given to using existing sites (dispensing with pits and silos) and exploiting cheap covering materials available on the farm which can be sealed with mud.

Key words: Straw-treatment, urea, sealing with mud, smallholder farmers


Introduction

The total area of Balochistan (one of the four provinces of Pakistan) is close to 35 million hectares or almost 45% of the country's total; about 90% of this consists of arid grazing lands and desert. The total annual rainfall varies from an average of 100 mm in the west to 300 - 400 mm in the north-east. Rains, some in the form of snow, fall mostly during the winter months of December - March.

Data from the 1986 livestock census reveal that Balochistan province accounts for almost one half the sheep (11.1 million) and one-quarter of the goat (7.3 million) population of the entire country. Estimates of dry matter (DM) production from Balochistan's rangeland vary from 2.5 to 4.2 million tonnes. Feed DM demands, however, as dictated by livestock numbers, are 8-9 million tons indicating that rangelands may provide only between one-third and one-half of the feed requirement for satisfactory performance. Supplementary roughage, largely as cereal straw (predominantly wheat) amounts to an estimated 1 million tons, and more is purchased from neighboring provinces, most of which is fed during the winter months when feed shortage is most critical.

A steady decline in underground water reserves, diverted to cash crops, implies that irrigated fodder for livestock feeding, which now plays a minor or insignificant role, will gain little or no acceptance in the future. As cereal straws comprise more than 80 -90% of the winter roughages, it was of great importance to explore the potential improvement in small ruminant (sheep and goat) production through practical and low-cost systems of treating these fibrous feed resources with urea.

Straw treatment in developing countries

Some factors to be considered

The concept of increasing the nitrogen content and nutritive value of low-protein roughages including cereal straw by means of urea and ammonia treatment is more than a century old and has been researched and tested in the developed world during the past 50 years. Conditions in the latter precluded its widespread acceptance: foremost among these being the relative abundance of alternative feeds of much higher quality, in addition to the high labour and other treatment costs.

The situation in many developing countries, however, is markedly different. In dryer zones, water is often a limited resource and is understandably reserved for growing food crops for the ever-increasing human population, with green fodder for livestock, although critical to obtaining improved performance, forcibly relegated to a lower priority or disregarded entirely. On the other hand, cereal straws generally comprise most of the supplementary roughages for winter or dry season feeding. Since feeding these low-protein roughages on their own results in considerable liveweight losses much effort has been directed to up-grading them through treatment with either ammonia or urea solutions. Untreated straws having 2-4 % crude protein initially have, after treatment, "potential" crude protein levels of 7-12 % which is sufficient for maintenance of liveweight. This contrasts with liveweight losses in sheep of about 100 g per day when fed untreated straw without supplemental nitrogen (Ghadaki et al 72). The use of a cheap source of nitrogen such as urea to improve the nitrogen content of straws makes a good deal of technical sense but other factors enter the equation and vary in significance from one country to another.

It must be remembered that in the eyes of smallholder farmers who have little or no formal education (over 75% of rural farmers in Balochistan fit into this category) urea treatment of straw is unknown technology and farmers are wary both of committing some of their "precious" straw for treatment and the fear of ensuing death losses. The overriding need is for a system which is both practical and easy for farmers to adopt and, above all, is cost-effective; without these conditions being met there is little likelihood of long-term success and sustainability. Few or no extra structures (except, perhaps, a limited number made of local materials) should be involved. Raw materials, especially urea, should be produced within the country and be widely available at a competitive price; also materials, including those needed for covering stacks, and other supplies should be readily accessible. The margin between the cost of urea-treated straw and alternative roughages must be sufficiently attractive.

Scale of operation and success rate to date

Much of the early work on straw treatment in developing countries concentrated on small scale research projects with little or no on-farm application. Small scale research, starting in the 1970's, in Bangladesh (Dolberg et al 1981) and to some extent in other countries in the Far East identified suitable means of treating small quantities of straw, up to 200-300 kg in most instances, in simple structures such as underground pits and over ground silos and stacks. The on-farm application rate, however, was insignificant. Various factors contributed to the lack of impact, most notably the difficulty for farmers to carry out the technical job unaided, the cost and extra work of constructing silos, cost and availability of covering materials plus the unsatisfactory cost: benefit ratio of using urea to treat straw versus its use to raise rice yields so vital to family food supply and survival. While the technical benefits could easily be substantiated, the obstacles cited and the farmers' own immediate priorities implied that the technology could not establish and maintain firm roots within the farming community.

In addition to Bangladesh, urea treatment of straw has been tested in pilot research projects in many developing countries but with little or no impact in boosting the supply of urea-treated straw for farmers at large. One notable exception in recent years is China where, with the assistance of an FAO project, quantities of straw treated on-farm with urea rose from a mere 30,000 tonnes in 1985 to an estimated 6 million tons by the year 1992 (Dolberg and Finlayson 1995). Relatively small lots of straw were treated with urea, using over ground stacks and brick silos which were covered with plastic. The treatment procedure differed little from that practiced in Bangladesh and one might justifiably wonder why the adoption rate in China should be so much greater.

As pointed out by the authors, one of the reasons for the rapid uptake was due to the low value/cost of the straw. Because of the environmental pollution resulting from traditional post-harvest burning of straw, Government support was given to divert more straw to animal feeding thereby boosting beef production. Supports included providing trained technical assistance at village level, low interest (0.7% per month) credit and guaranteed supplies of urea (200,000 tonnes at subsidized rates in 1992). There may be a lesson here for other countries; while financial incentives of the Chinese variety may not be possible or desirable elsewhere, there is little doubt that Government promotional and technical supports, coupled with farmer awareness and motivation, are intrinsic ingredients for long-term success. The Chinese experience also suggests that the desirable combination of favourable factors for success (including human) will only be found in certain regions and countries.

Earlier results with straw treatment in Turkey

The senior author worked in Turkey on a UNDP/FAO - funded project (TUR/87/018) located at Konya, Central Anatolia, in two separate missions (May-July, 1989 and January - March, 1990). One of the tasks undertaken was to investigate the potential for up-grading wheat straw and to carry out several demonstrations (O'Donovan 1989, 1990). The province of Konya is the biggest producer of wheat in Turkey and vast quantities of straw provide in excess of 80 - 90% of the supplemental roughage supply for livestock (largely sheep and goats). In addition, urea produced in the country was readily available as was a variety of plastic sheeting for covering and sealing the ensiled material.

One of the biggest problems was the construction of a pit or silo, an initial task in the straw treatment process that discouraged many farmers. A simpler and more practical structure was therefore developed to minimize or eliminate completely fixed structures in the form of pits and silos. Over ground square or rectangular stacks of straw were built during the Konya project, each containing from one-half to 2 tonnes of straw. After one or two stacks were built, the under layer of plastic sheeting was dispensed with and no ill-effects were noted. Thus, it became the standard practice to use only a top sheet of plastic which, when tucked securely under the stack to exclude air, allowed for good quality treated straw to be made and preserved.

Making straw stacks in the open, however, was not the ideal system. Much care was needed in properly building the stacks (especially at the corners). Moreover, and much more important, such stacks needed a good deal of plastic top sheeting to extend over the top, the four sides and about 15 cm tucked underneath. As plastic sheet tends to be rather expensive, especially the 0.2 mm thickness needed to minimize puncturing and a possible second or third reuse, another option needed to be tested.

Inspection of a number of possible on-farm sites indicated that existing walls (often made of mud) of farm houses could be utilized to good effect. Choosing a corner location permitted the use of two walls. Since only the front and one side of the stack were exposed, these were the only surfaces that had to be covered. In some instances, an existing structure having 3 walls was used, which reduced further the plastic needs.

All of the subsequent straw treatment demonstrations at selected project sites throughout Konya province were carried out capitalising on these existing walls. The treated straw was of good quality and was fed to both sheep and cattle including dairy cows. A feeding trial conducted with sheep demonstrated that urea-treated straw plus a mineral supplement was capable of maintaining liveweight. Farmers who witnessed first-hand the superior feeding value of urea-treated straw were quick to repeat the procedure, often treating larger amounts. Visual aids (including a video) were used in later training sessions for both extension staff and farmers. The technology was simplified to the point where farmers could, after one or two demonstrations, carry out the task themselves
unaided.

Refinements in Balochistan, Pakistan

After the experience in Turkey, it was a question of further simplifying and refining the straw treatment procedure and adapting it to conditions in Balochistan. The predominance of wheat straw as roughage in Balochistan justified its full exploitation for livestock feeding. Improvements were foreseen in two areas:

Efforts in Balochistan were therefore concentrated on testing alternative and cheaper forms of covering, preferably those readily available on farm. Tests revealed that plastic sacks, either new or used, cut open to increase surface area, could replace the plastic sheet if the sacks in turn were covered or plastered with a 1-2 cm layer of mud to provide an effective air seal. The sack plus mud cover was about one-quarter of the cost of plastic sheet. Subsequently, all straw treatment applications employed this simplified lower-cost procedure. The quality of the straw treated by this simplified method was as good as, and in many case superior to, that achieved through the use of plastic sheet.

This latter development opened doors to the more rapid uptake and adoption of the technology at peasant farmer level. Other cheaper covering materials, besides plastic sacks, were also tested and adopted; these merely provide a base or holding medium for the layer of mud on top, with which care had to be exercised to ensure a uniform cover over the straw and with no air leaks.

Important considerations in straw treatment

Straw availability and treatment time:

Wheat straw harvesting occurs in Balochistan for the most part during the summer months of June and July and, as expected, prices are lowest then, often one half of those prevailing during the later winter months of feed shortage from January to March. It made good economic sense, therefore, to buy (and store, if necessary) as early as possible after June. In both Turkey and Balochistan straw is chopped at harvest time making it relatively easy to handle and treat with urea and also improving the absorption capacity. On the negative side the chopped straw is somewhat more difficult to build into well-formed stacks and shapes.

Site selection

Some other features of site selection are important. As stack heights are about 1.25m, the containing/supporting walls should be at least this height (marginally higher at 1.4 - 1.5m is ideal). These walls should be devoid of holes which, in allowing air to enter, can spoil the ensiled straw. The floor should slope gently allowing any excess liquid or solution to seep to the lowest layer to drain out. It is most desirable that straw should be treated as near as possible to where the animals can later be fed. If possible, a somewhat sheltered site is preferred, away from the sun's direct heat radiation. As poultry like to perch on top of the stacks and peck at the covering layer and thus expose some of the material to air and spoilage, simple protection methods are recommended. Ideally stacks should be sited away from the reach of poultry.

Equipment and supplies:

In Balochistan a 200 litre capacity plastic container was used for convenience in the preparation of the water-urea solution; however, barrels cut in half and even smaller capacity utensils commonly found on the farm can be employed. Tin spray cans of 15 litre capacity, with nozzles, were used to distribute the water-urea solution evenly over the straw layers. A few plastic buckets for measuring urea and water are also used. Fertilizer grade urea was employed and is available throughout Balochistan (Pakistan is self-sufficient in urea production). The covering material for stacks was originally locally-produced plastic sheeting of 0.1 to 0.2 mm thickness which was later replaced by plastic sacks (widely used locally) and mud cover.

Stack sizes:

The stack size is determined to a large degree by the flock size (sheep and goat). In Balochistan most flocks range in size from 10 to 40 and, therefore, large stacks are not necessary. Moreover, since urea-treated straw is reserved for critical feed shortage periods or times of need (eg:: late gestation, early lactation), only a proportion, perhaps 30-50%, of a particular farmer's straw supply may be treated.

Under Balochistan's conditions and needs, convenient stack sizes tested and employed were such as to contain either 500 or 1000 kg of straw. Suitable dimensions for the former were 2m (length) x 2m (width) x 1.25m (height). This was based on the estimate (confirmed by weighing certain lots of straw) that 1 cubic metre of chopped compressed straw weighs between 80 and 100 kg. Therefore a stack size of 5 m3 (2m x 2m x 1.25m) contains about 500 kg of straw. For 1 tonne a practical and convenient size is 4m (l) x 2m (w) x 1.25m (h). Under average working conditions, it takes 1 - 1 .5 hours to treat (including covering/sealing) 500 kg of straw and 2 - 2.5 hours for a 1 tonne stack. With some dairy farmers, 2 tonne lots were prepared in sequence side-by-side (with only a mud dividing wall) so that as feeding of one stack began, a second was treated for later use.

Procedural matters:

The ratio of water-urea solution to straw practiced in Konya, Turkey was 1:1 (500 litres of solution for 500 kg of straw) and it gave a moist and soft ensiled material. In the arid areas of Balochistan, where water availability can occasionally be a problem, it was decided to test different ratios of solution to straw, varying from 1:1 (considered to be the optimum and giving best results) to 0.5:1 (250 litres of solution to 500 kg of straw). While the latter ratio resulted in satisfactory preservation, the finished material was rather dry; if water supply is not a problem the 1:1 ratio or levels between 0.7:1 and 1:1 are preferred.

It is stressed that adequate covering and the exclusion of air (also water that may seep in) is of paramount importance in obtaining a good-quality finished product. The used sacks and mud cover are recommended as the least cost solution.

The stack of treated straw was opened usually after a minimum of 3 weeks. If it is well sealed, it can be left for several months without adverse effects. In one instance, ensiled straw in one area of Balochistan, when opened after one year, was found to be of acceptable quality. It is best to synchronise treatment with feeding whenever possible. As experienced with the farming communities in Balochistan, assistance had to be given during the initial opening of stacks and the feeding of treated straw. The need to wait some 1-2 days for animals to become accustomed to the treated straw is one factor. More important is that animals should not be given access to more palatable feeds, either as grazing or in confinement.

Lessons learned

The various stages in developing and refining urea treatment of straw provided experience and information which could usefully be applied to the introduction of any new technology to farmers, particularly those with low levels of literacy. Four important criteria should be met:

References

Dolberg F, Saadullah M, Haque M and Ahmed R 1981 Storage of urea-treated straw using indigenous material. World Animal Review. 38: 37-41.

Dolberg F and Finlayson P 1995 Treated straw for beef production in China. World Animal Review. 82: 14-24.

Ghadaki M B, O'Donovan P B and Behesti R D 1972 Comparison of three straw-based rations for ewes during pregnancy and the pre-lambing response to selected levels of concentrate feeding. Technical Report No. 18 FAO Project 193 and Animal Husbandry Research Institute, Hyderabad, Iran.

O'Donovan P B 1989 Final report of consultancy mission (May-July) to UNDP/FAO Project TUR/87/018, Konya, Turkey.

O'Donovan P B 1990 Final report of consultancy mission (Jan-March) to UNDP/FAO Project TUR/87/018, Konya, Turkey.

O'Donovan P B 1996 Status of and scope for small ruminant nutrition in Balochistan. Report prepared on UNDP/FAO Project Pak/88/050, dated March, 1996, Balochistan, Pakistan

Received 15 August 1997

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