Studies on actual and residual effects of phosphatic fertilizers on growth and yield of soybean and corn
1992
Chairoj Wongwiwatchai
Three consecutive field trials were conducted to assess the actual and residual effects of fertilizer P, municipal compost and crop residue on soybean and corn grown on Satuk soil series. The experimental design was a split-plot having 2 main plots and 12 sub-plots with 3 replications. Main plots comprise 1) addition of municipal compost and 2) incorporation of crop residue after each harvest. Twelve fertilizer treatments in the sub-plots were checked plots and factorial combinations of 3 P-rates and 3 P-sources i.e. rock phosphate (RP), triple superphosphate (TSP) for soybean and monoammonium phosphate (MAP) for corn and mixtures of RP:TSP and RP:MAP at 3:1 P-ratio based on available P contents. By average over 3 consecutive crops, the response of soybean to P sources were in the order of TSP RP+TSP RP. Plant response to TSP was the highest for all 3 crops, but the magnitude of response tended to decrease with cropping seasons. For RP, this was a reverse in which the first crop showed the lowest response but tended to increase thereafter. Comparatively, crop response to RP+TSP were comparable and consistent for all 3 planting seasons. Generally, maximum response to P-rate was attained at 18 kg P2O5 per rai. For municipal compost and crop residue incorporated, the influence on promoting crop growth were pronounced for the second and the third crops. For the first crop season, corn responses to P-sources were similar to that of soybean whereas the responses of the second and the third crop were not significantly different. Generally, the responses of corn to P-rates, municipal compost and incorporation of crop residue were not pronounced. Large initial application of P fertilizers regardless of forms are appropriated practices for corn and soybean in the long run whereas addition of RP alone or in combination with other water soluble P-sources gave higher and longer residual effects on crops than using only water soluble P fertilizers.
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Эту запись предоставил Kasetsart University