The effect of incorporation time of different crops on the residual effecton spring cereals

The effect of the time of incorporation of different green manures and barl ey residues on the grain yield of spring cereals in two successive seasons was studied in seven field trials. Annual hairy vetch (Vicia villosa Both), red clover (Trifolium pratense L.), westerwold ryegrass (Lolium multifloru m Lam. var. westerwoldicum) and straw of spring barley (Hordeum vulgare L.) were incorporated into the soil by ploughing in early September, late Octo ber and the following May, and by reduced tillage in May. Spring barley was established in the following spring, and spring oats (Avena sativa L.) one year later. In general the grain yield of spring barley after legumes was similar to th at after barley, in spite of the fact that N fertilization was reduced by 4 0 kg ha(-1). The two autumn ploughing treatments resulted in a good yield o f spring barley more reliably than did the spring incorporations. Because d elayed autumn ploughing did not decrease the grain yield, a delaying proced ure can be recommended for its potential of decreasing nitrogen leaching. S pring ploughing could be used on all but clay soils. Incorporating ryegrass or red clover in spring by using reduced tillage often decreased the grain yield of barley. Timing of incorporation did not have a consistent effect on the grain yield of oats in the third experimental year.