Some Effects of Fertilization on the Yield, Botanical and Chemical Composition of Irrigated Grass and Grass-Clover Pasture Swards

Abstract

In an irrigated pasture experiment on Vancouver Island, on a soil deficient in available nitrogen and potassium but apparently containing sufficient available phosphorus, calcium and magnesium for adequate plant growth, an irrigated Ladino clover-grass mixture greatly outproduced a grass mixture on a forage, protein and mineral nutrient yield basis. In order to attain even a moderate yield with a grass mixture, heavy fertilization with nitrogen and potassium was necessary. Nitrogen fertilization was not essential to high yields with the Ladino clover-grass mixture. Nitrogen fertilization tended to decrease the per cent Ladino clover and the protein and calcium content in the clover-grass forage and increased the protein content of the grass herbage. The calcium content of the grass herbage was decreased by nitrogen fertilization. The phosphorus and magnesium contents of the clover-grass and grass herbage were not appreciably altered by nitrogen fertilization. Decreasing the time interval between nitrogen applications resulted in a more even production of dry matter over the growing season but did not increase the total seasonal yield. Potassium fertilization increased the yield of both mixtures and increased the per cent clover in the grass-clover sward. Multi-annual potassium applications were required for the elimination of plant potassium deficiency symptoms and the applied potassium was quickly absorbed by the plants. Grass herbage contained more potassium, slightly more phosphorus and less calcium, magnesium and nitrogen than grass-clover herbage.

The effect of fertilizer nitrogen, phosphorus and potassium on the calcium, magnesium and phosphorus status of pasture cut for silage

“…The negligible effect of potassium on phosphorus concentration of herbage found in these experiments supports results reported by Stewart & Holmes (1953), Gardner et al (1960), Rahman, McDonald & Simpson (1960) and Koehler et al (1957). The tendency for potassium to reduce phosphorus concentration in the second cuts agrees with the findings of Reith et al (1964), Heddle & Crooks (1967) and Mudd (1970).…”

“…The negligible effects of applied phosphorus on herbage calcium found in these experiments are similar to those reported by Watkin (1957), Gardner et al (1960), Saunders, Taylor & Gold (1963), Reith et al (1964) and Heddle & Crooks (1967).…”

“…The negligible effects of applied phosphorus on herbage magnesium, apparent in these experiments, are in agreement with Gardner et al (1960), Hemingway (1961, Saunders et al (1963), Reith et al (1964) and Heddle & Crooks (1967). In contrast, Watkin (1957) found that applied phosphorus increased herbage magnesium concentration.…”

“…Although the effect of applied potassium in reducing herbage magnesium concentration was significant only at farm A, a site where available soil potassium was exceptionally high, there was a tendency for the higher rate of potassium application to reduce herbage magnesium concentrations at farm B in 1969. Reduction of herbage magnesium by potassium application has been noted by Stewart & Holmes (1953), Gardner et al (1960), Kemp (1960), Wolton (1960), Hemingway (1961), Hunt, Alexander & Rutherford (1964, Heddle & Crooks (1967) and Adams (1973).…”

“…Only in the final year of the experiment.when the clover content of the sward was quite low, was there any significant effect of phosphorus at the second cut. Melville & Sears (1953), Norman (1956), Gardner et al (1960), Saunders et al (1963), Reith et al (1964), Widdowson et al (1966), Heddle & Crooks (1967) and Adams (1973) all found that applied phosphorus increased the phosphorus concentration of herbage.…”