EFFECTS OF SUBSOILING AND DEEP INCORPORATION OF P-FERTILIZERS AND K-FERTILIZERS ON THE YIELD AND NUTRIENT-UPTAKE OF BARLEY, POTATOES, WHEAT AND SUGAR-BEET GROWN IN ROTATION

A small-plot experiment on sandy loam soil at Woburn tested the effects of subsoiling by hand and of incorporating a large dressing of P and K fertilizer into the subsoil. The treatments were applied once in 1973 and their effects were assessed from 1974 to 1977 on the yields of, and N, P, K uptakes by, barley, potatoes, wheat and sugar beet grown in rotation. All crops were present each year and all plots received annual seedbed dressings of N, P and K appropriate to the crop. Dolomitic limestone was applied once in the rotation. The effects of the treatments on P soluble in 0.5 M.NaHCO3 and exchangeable K in surface and subsoils were measured.Subsoiling alone increased the 4-year mean yield of wheat by 21, of barley by 24 and of sugar from sugar beet by 11. Mean yield of potatoes was unaffected.Incorporating P and K into the subsoil increased the mean yield of potatoes by 16 and further increased mean yield, in addition to the effect of subsoiling, of barley by 20 and of sugar by 4. Mean yield of wheat was not further affected. © 1979, Cambridge University Press. All rights reserved.