The effects of subsoiling and deep incorporation of P and K fertilizers on the yield and nutrient uptake of barley, potatoes, wheat and sugar beet grown in rotation

SUMMARY 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. Ths 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-NaHCO 3 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.