MOISTURE SUPPLY AND YIELD OF WINTER WHEAT IN DIFFERENT ZONES OF STAVROPOL TERRITORY
In dry conditions, the crops supply with moisture is crucial for the yield formation. The study was carried out in 2009-2010 in the arid zone in Prikumskaya experimental breeding station and in the unstable moistening zone in Stavropol Research Institute of Agriculture. The aim of the research is to study the moisture supply of winter wheat crops by various forecrops and zones of Stavropol territory. Moisture reserves in 1 m soil layer before sowing in the arid zone depending on the forecrop were 75-108, and in the unstable moisture zone - 103-128 mm. By the end of autumn, moisture reserves were significantly replenished in the arid zone only by bastard fallow (18.1 mm), while in the unstable moisture zone by all forecrops (20.8-33.1 mm). By the beginning of spring vegetation, its maximum reserves were in the arid zone by seeded fallow (144.1 mm), in the unstable moisture zone - by bastard fallow (163.6 mm). Increased by this time moisture reserve by these forecrops was 53,6 and 27,6 mm, respectively, with an assimilation coefficient of the cold period precipitation 0,31 and 0,16. The greatest total moisture losses in all zones were by bare fallow (446,5 and 530,6 mm). On all nutrient statuses the maximum yield is obtained by bare fallow: 3,67 t/ha in the arid zone and 4,76 t/ha in the unstable moistening zone. In the arid zone 0.30 t/ha less is harvested by the seeded fallow and 1,57 t/ha of grain less by bastard fallow than by bare fallow. The lack of grain by these forecrops was respectively 0,99 and 2,25 t/ha in the unstable moisture zone. The most rational use of moisture with winter wheat crops for the formation of 1 ton of grain yield was by bare fallow. As the forecrop worsen, the efficiency of moisture use decreased and the water consumption coefficient increased.