Studies on phosphate fertilizers in rice-groundnut sequential cropping system in Lampang soils
1991
Chairerk Suwannarat | Amnat Suwanarit | Chamchan Vijarnsorn (Kasetsart Univ., Bangkok (Thailand). Faculty of Agriculture. Dept. of Soil Science)
To study the efficiency of phosphate fertilizers in rice groundnut sequential cropping system, the on-farm research was conducted in Amphoe Muang, Lampang province in two successive years. In the first year two kinds of P-fertilizer namely triple superphosphate (TSP) and rock phosphate (RP) were tested for the RD 6 glutinous rice in rainy season. The application rates were 9 kg P2O5/rai of TSP compared with 3 rates of RP: 50, 100 and 200 kg/rai. After harvesting rice, the groundnut, Tainan 9, was grown during dry season in order to study the residual effect of P on the growth and yield of this legume. In addition, one extra treatment "liming (200 kg of CaOH2/rai)+residual TSP" was added into the treatments of the groundnut. The experimental results can be concluded that rice did not show any response to P whereas the residual P affected both of the groundnut yield and the nutrient contents. Higher yield and higher contents of P in seed were observed in the plots of residual P. The residual effect of the TSP was more or less the same as that of the RP. Liming in the residual TSP plot showed the highest groundnut yield. To study the residual effect of the phosphate fertilizers applied in the first year, the RD 6 glutinuos rice was planted in rainy season of the following year and the Tainan 9 groundnut was grown in dry season. These two successive crops were grown without application of those phosphate fertilizer or lime. The results indicated that there was no residual effect of the phosphate fertilizers on the rice yield whereas the effect was evident in the groundnut one. The highest groundnut yield was observed from the residual TSP+lime plot whereas the residual effect of RP at the rate of 50 kg/rai was slightly lower than that of the former with statistically no significant difference.
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