Soil available nutrients and rice yield with silicon and phosphorus fertilization

It had been confirmed that silicon（Si） could enhance P efficiency in paddy soil, but the interactional effect of different ratio of Si and P fertilization was rarely documented. Therefore, the study aims to understand the effects of fertilization with different ratios of Si and P on soil fertility and rice yield. Three levels of Si and P fertilizers treatments were carried out through a pot experiment（0, m and h mean light, moderate and high treatments respectively）, nine different treatments included Si0P0, Si0Pm, Si0P0, SimP0, SimPm, SimPh, SihP0, SihPm, SihPh. Sodium silicate and calcium dihydrogen phosphate were used as Si and P fertilizers respectively. Each treatment had five replications and random arranged. After rice harvest, soil samples （about 1 kg fresh weight） were collected from each pot, air dried and sieved through a 2 mm stainless steel screen, then stored for pH, available nitrogen（N）, phosphorus, potassium（K） and silicon analysis. Rice yield components were also determined. The data was analyzed in Microsoft 2003, SPSS 18.0（ANOVA）. Means were tested using the least significant difference（LSD） with a significance of P＜0.05. The soil pH value was significantly increased with the amount of P fertilization when compared with Si0P0 treatment under light and moderate Si level, but showed no difference under high Si level. Under the same P level, the soil pH value was significantly increased with the application amount of Si. Under moderate Si level, the content of available N was significantly increased with the application amount of P, whereas, the amount of Si fertilization showed no significant effect on available N under the same P level. The available P was significantly increased with the application amount of Si under the same P level. The highest available P content occurred with treatment SihPh. Under moderate Si level, the available K was significantly increased with the application amount of P, but showed no difference under light and high Si level. Available Si was significantly increased with light and moderate P application. Under light and moderate Si or P level, the rice dry matter weight increased significantly with the application amount of Si or P. Rice grain yield increased significantly with the P application amount under light and moderate Si application. The highest grain yield for the nine treatments occurred with SimPh which increased by 74.78% compared with Si0P0. In this pot experiment, application of moderate Si with P fertilization could enhance the soil pH, available N, P, K and Si, rice dry matter weight and grain yield in paddy soil. There had significant interaction between different amount of Si and P applying. ［Ch, 4 tab. 13 ref.］