will protect the soil surface, but it tends to blow away, leaving the surface bare and vulnerable to erosion. Heavy grazing not only removes all the stubble but pulverizes the soil surface, increasing the risk of wind erosion. In Syria, wind erosion of topsoil can be severe after harvest and stubble grazing. Erosive wind occurs mainly during June and August when soil is dry and the surface cover very sparse. Grazing should be controlled to leave sufficient surface stubble to protect the soil from erosion.  We need to understand all this--and yet  grazing of stubble has received little research attention and there is very little published on the grazing of cereal stubble.
        The environmental implications go beyond wind erosion and pollution. Demand for animal products in West Asia and North Africa (WANA) is increasing as a result of population growth and increased urban consumption. Sheep and goats are the most important livestock species in WANA region, with a population of several hundred million animals. This large population has led, in a chain reaction, to overgrazing, degradation and decline in productivity of the natural grassland (see The battle for the steppe in Caravan No.3); this has increased the importance of cereal crops for feeding ruminants. It is, in fact, an important part of the farming system--and of the regional environment, as well as its economy.
        The close integration of livestock and crops in farming systems in the WANA region plays a key role in determining the current crop production strategy of the majority of farmers in the region. In the period between harvesting cereals in June and sowing the new criop in October, stubble grazing (i.e. on-field post-harvest residue) is the most important source of nutrient for small ruminants. Moreover, the stubble-grazing period coincides with mating and pregnancy in the flocks. As nutrition before mating and in the first month of pregnancy can have a major effect on the fertility and prolificacy of the flocks, stubble grazing has important implications for their performance during the whole year.
        Is stubble alone enough at this period? ICARDA decided to look at this in more detail. Its Pasture, Forage and Livestock Program (PFLP) surveyed farm practice in northern Syria and started experiments on the effects of stocking rate and feed supplementation on stubble intake.  The sheep were the hardy fat-tailed Awassi breed common in the region (see When sheep's tails had wheels in
Caravan No. 1).
        The experiments illustrated the change in level of nutrition that occurs as stubble becomes depleted with time or heavy stocking. Sheep usually graze stubble at mating time; better nutrition at this time makes lambing earlier and increases the number of lambs born in the flock. Offering small amounts of supplement--cottonseed meal or barley and cotton seed meal--to ewes grazing barley stubble increased body weight at mating, and reduced the time required to conceive. Responses were greater in ewes receiving supplements with higher protein concentration.
        Future work will address problems at the farm level--in particular, the practicality of using non-protein nitrogen (urea blocks) to reduce the cost of nitrogen supplementation, and whether the findings are applicable to sheep grazing wheat stubble. There is also a possible link here with the broad range of other work that PFLP is doing on the use of feed and forage legumes to replace continuous cereal cultivation (see Feed for the future in Caravan No.1). These legumes, too, are  an important source of feed, and good for the soil (legumes fix nitrogen). Other relevant activities at ICARDA include the breeding of high-yielding cereals for good feeding-quality straw (see A broad spectrum of barley in
Caravan No. 2). Careful, integrated research in a farming-system context could all but eliminate the economic pressures that lead to stubble burning.
        That is how it should be. We are balancing environmental and economic factors within the context of the farming system.

Dr Safouh Rihawi is Research Associate (Animal Production and Nutrition), Pasture, Forage and Livestock Program, ICARDA.

n much of the West Asia and North Africa (WANA) region, the landscape in the wheat-growing areas is disfigured for several weeks after the harvest by thick black pillars of smoke, rising from the fields where the cereal stubble is burned. It's a pollutant; and it's bad for the soil, exposing it to wind erosion. As with so many issues in agricultural development, the farmers are reacting to economic pressure. They do it mainly so that they can put the field back into production quickly, usually under when they are irrigation. There is a spiralling demand for cereals in WANA, and farmers can hardly be blamed for wishing to maximize their returns from the land.

        But stubble burning may actually be economically disadvantageous. Crop residues are valuable as animal feed in WANA--that might be money going up in smoke!
        Many farmers do, in fact, take that view. Countries in the WANA region and many other regions around the world have a dry season when sheep graze cereal stubble after harvesting. Cereal stubble is an alternative to dry annual pastures in summer and autumn. This relieves grazing pressure on other parts of the farm; and increases returns, taking advantage of the considerable quantity of the dry matter for animal production. So stubble may be an important part of the gross economic return from crops. In fact, burning of stubble is very rarely practiced in in Syria in areas with areas with rainfall below about 325 mm, where every stalk of stubble is required for grazing.
        However, in the past, in many regions particularly with rainfall of over 400 mm, farmers have regarded stubble as an unwanted by-product, and stubble management by fire has been an easy solution. There are, in fact, potential disadvantages in retaining stubble, as it may make seeding and weed control difficult, temporarily tie up nitrogen, and may assist to carry-over of crop disease.
        Even so, in the long term, retaining stubble is better for the land. It can maintain or slightly increase soil organic matter and structural stability, and reduce erosion. These benefits can be important if stubble retention is combined with grazing. And  there is an increasing awareness now exist of the need to retain surface cover to protect the soil from wind and water erosion. Stubble reduces erosion by reducing wind drag on the soil surface, physically protecting the surface from the impact of blown-in sand and intercepting moving soil particles.
        But leaving stubble in place doesn't eliminate wind erosion entirely. Most stubble fields in WANA are grazed in summer by sheep, causing plants to be trampled, eaten and removed. The prostrate stubble resulting from grazing