DIFFERENCES IN BARLEY-GRAIN YIELDS AS A RESULT OF SOIL VARIABILITY

Field scale variability in the grain yield of barley in 1989 was inves tigated in 62 field plots in a Dutch polder area, and compared to soil - and simulation-type characteristics. Total grain mass varied between 3409 and 6019 kg/ha, and grain moisture content between 13.1 and 14.7 %. Soil profile descriptions and soil characteristics were used as ba sic input data for simulations. Soil water flow was simulated at 119 l ocations with the LEACHM model, for the purpose of quantifying spatial variability in transpiration deficits in the growing season. Both soi l- and simulation-type characteristics were translated from point valu es to spatial averages for the harvested fields, using kriging. Kriged characteristics were correlated with yields, and used to construct tr ansfer functions. Simulated transpiration deficits during sensitive cr op development phases showed negative correlations with grain yield. T ransfer functions explained at maximum 68.2 % of the variance in the y ields.