Crop yield, P uptake and soil organic phosphorus fractions in response to short-term tillage and fertilization under a rape-rice rotation in central China

We conducted a 3-year field experiment on an Anthrosol paddy soil to investigate changes in crop yield, P uptake and soil organic phosphorus (P) fractions after 3 years of conventional tillage (CT) conversion to no-tillage (NT) under a rape - rice rotation in central China. Treatments were established following a split-plot design of a randomized complete block with tillage practice as the main plot and fertilizer as the sub-plot treatment. The yields of rape and rice ranged from 1378 to 2264 kg ha(-1) and from 5895 to 9453 kg ha(-1) across 3 years, respectively. Moreover, P uptake for rape and rice (aboveground) varied from 3.9 to 10.4 kg ha(-1) and from 9.5 to 32.0 kg ha(-1), respectively. Fertilization significantly enhanced crop yields and P uptake, but tillage did not affect the yields and P uptake. Fertilization significantly increased total P concentrations, acid phosphatase activity, Bray-1 P and labile organic P in the 0-5 cm soil layer. Compared to the CT treatments, the NT treatments had significantly higher acid phosphatase activity, total P, Bray-1 P, total organic P and organic P fractions in the 0-5 cm soil layer but lower organic P fractions in the 5-20 cm soil layer. Therefore, our results suggest that short-term NT does not enhance organic P concentrations in the 0-20 cm soil layer, and only improve P availability on the soil surface.