Liquid manure as a grassland fertilizer. I. The response to liquid manure and to dry fertilizer

Abstract

1. A small-scale plot experiment was conducted for a 3-year period, 1958–60, to study the comparative effect of applications of liquid manure, water and dry fertilizer on the yield and quality of an established meadow fescue and white clover sward.2. The liquid manure was collected from a cowshed and contained on average 0·23% N, 0·003% P2O6 and 0·48%K2O.3. The treatments applied each year were: (1) control, no fertilizer; (2) and (3) a low and a high rate of water equal in weight to the liquid manure applied in treatments (4) and (5) respectively; (4) a low rate of liquid manure supplying 75 lb. nitrogen and 159 lb. K2O; (5) a high rate of liquid manure supplying 150 lb. nitrogen and 318 lb. K2O/acre; (6) and (7) liquid manure as in (4) and (5) plus 82 lb. P2O6/acre; (8) a low rate of normal dry fertilizer supplying 87 lb. nitrogen, 82 lb. P2O6 and 84 lb. K2O/acre; and (9) a high rate supplying 174 lb. nitrogen, 82 lb. P2O5 and 168 lb. K2O/acre.All treatments were applied in five equal dressings each year, one for each cut, except the P2O5 which was applied twice a year.4. The yields of herbage dry matter and crude protein were not affected by the water treatments, but both the liquid-manure and dry-fertilizer treatments caused significant increases in yield. The application of phosphate on the liquid-manure treatments had no significant effect on yields.5. The crude-protein contents of the herbage on the different treatments did not show any large or consistent differences.6. The botanical compositions of the swards were significantly different at the end of the third experimental year. On the liquid-manure treatments the content of clover had increased and the meadow fescue and dicotyledonous weeds decreased compared with the control. The mean content of clover in the swards at the end of the trial was 32, 18 and 15% on the liquid-manure, dry-fertilizer and control treatments respectively.7. There were no major differences between either the pH values or the contents of P2O5 in samples of soil on the different treatments after 3 years, but the average K2O value on the control and two water treatments was almost half that on the high liquid-manure treatment.8. The mineral contents of the herbage were determined. In 2 of the 3 years the liquid-manure treatments produced herbage with high K and lowered Ca, Mg and Na contents. The Mg content of the herbage on the four liquid-manure treatments averaged 0·26%.