Abstract
The possibility of improving the soil phosphorus status by a store dressing with rock phosphate has been studied in two field trials of five years standing. Hyperphosphate Reno was applied to the nurse crop of a red clover-timothy ley in amounts of 0, 1000 kg/ha, or 2000 kg/ha, respectively. The split-plot technique was used to study the response of the ley to an additional annual application of 200 kg/ha of superphosphate. The soil analyses distinctly proved that, in spite of a careful working in of the hyperphosphate with a spade harrow, the fertilizer had not penetrated deeper than to the layer from 1 to 3 inches, with a large part of it remaining in the top inch. The treatment with hyperphosphate had mostly increased the fraction of the calcium-bound phosphorus, and, to a very low degree, the aluminium-bound phosphorus. The effect of superphosphate could be detected only in the fractions of aluminium- and iron-bound phosphorus of the surface inch. Although the store dressing did not produce marked responses in the yields of either trial, the statistically significant negative interaction between the effect of it and of superphosphate may be taken to indicate that hyperphosphate was able to improve the phosphorus status of these soils to some degree. The analyses of the hay samples from one of the trials in the fifth experimental year showed that the store dressing, particularly with the higher amount of hyperphosphate was able to increase the phosphorus content of hay to a satisfactory level which was equal to that produced by the annual superphosphate dressing only. Their combined effect resulted in the production of hay dry matter containing more than 0.24 % of P. In one of the experiments the residual effect of the treatments on rye was studied. The response to superphosphate was highly significant, probably owing to the high demands of phosphorus by rye, connected with the overwintering conditions, and also to the fact that ploughing in of the ley had brought superphosphate phosphorus within the reach of the plant roots.
Highlights
The material is, far too small to give a reliable answer to this rather complicated question, but some interesting hints could be obtained, for further studies. It seems that a store dressing with 1000 kg/ha of hyperphosphate is probably too low to produce the effect wanted, and that even higher amounts than 2000 kg/ha cf hyperphosphate may be recommendable under our conditions for a really distinct result. It appears that the working of hyperphosphate into soil by a spade harrow did not, in spite of the very careful performance, bring the fertilizer deeper than to the layer from 1 to 3 inches, with a large part remaining in the surface inch
The possibility of improving the soil phosphorus status by a store dressing with rock phosphate has been studied in two field trials of five years standing
Hyperphosphate Reno was applied to the nurse crop of a red clover-timothy ley in amounts of 0, 1000 kg/ha, or 2000 kg/ha, respectively
Summary
The two field trials of five years standing were started in 1955 when the phosphate treatments for the nurse crop o:: a clover-timothy ley were the following: 1. No phosphate2. 1000 kg/ha of hyperphosphate3. 2000 kg/ha of hyperphosphateThe nurse crop in trial K was oats, in trial K it was barley. The two field trials of five years standing were started in 1955 when the phosphate treatments for the nurse crop o:: a clover-timothy ley were the following: 1. Since 1956 the effectiveness of the store dressing on the ley was compared with the increase produced by an additional annual application of 200 kg/ha of superphosphate. This was performed by applying the split plot technique. The plots in trial K 100 were 70 m and the plots of trial K 101 were m For the sub-treatments, the area of the plots were 35 2 and 40 m 2, respectively. The harvested m areas of the sub-plots were generally 16 or 17 m 2, Both the main treatments and the sub-treatments within a block were randomised, and the whole experiments consisted of four blocks
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