Abstract
BackgroundNutrient balance in rice paddy fields can change under different tillage management practices; however, the extent of the change may differ for various rice varieties. A field experiment was conducted over 2 successive years to clarify the effects of no-till and rice varieties on the apparent balance of nitrogen (N) and phosphorus (P). Four treatments: no-till/japonica rice (NTJ), no-till/glutinous rice (NTG), conventional tillage/japonica rice (CTJ), and conventional tillage/glutinous rice (CTG) with three replicates of each were established to test the hypothesis that no-till and japonica rice can improve the apparent balance of nutrients.ResultsThe tillage method and rice variety had interactive effects on the apparent balance of N and P. After the 2-year experiment, total N and P pools in the 20 cm surface soil layer were highest under the NTJ treatment (4757.0 kg N ha−1, 2428.5 kg P ha−1) and lowest under the CTG treatments (4726.3 kg N ha−1, 2412.0 kg P ha−1). Under no-till conditions, japonica rice had higher grain yield but lower straw biomass than that of glutinous rice. NTG treatment significantly increased the N and P content in rice grains and straw. The environmental losses of N and P in the rice fields mainly occurred during the rice season. Based on nutrient balance estimation, N losses in the NTJ, NTG, and CTJ treatments were reduced by 15.03 kg N ha−1, 11.55 kg N ha−1, 6.72 kg N ha−1, respectively, as compared with that of the CTG treatment. The corresponding P losses were reduced by 8.02 kg P ha−1, 7.84 kg P ha−1, and 3.96 kg P ha−1. In terms of economic benefits, NTJ also resulted in the highest actual income (2724.25 US dollars) and the highest ratio of production investment (6.40).ConclusionNo-till was more likely to maintain soil N and P nutrients than conventional tillage, and this advantage was most significant when planting japonica rice. In addition, no-till was conducive to N and P uptake by rice, but only japonica rice exhibited increased grain yield. Consequently, the NTJ treatment was recommended to improve the N and P balance.
Highlights
Nutrient balance in rice paddy fields can change under different tillage management practices; the extent of the change may differ for various rice varieties
We found that the tillage methods had a non-significant effect on grain yield and straw biomass (p > 0.05), but rice variety had a significant effect on rice yield (p < 0.05), which is consistent with the results of Qin et al [32]
Our study found that the no-till practice was able to maintain more soil N and P nutrients than conventional tillage, and this advantage was more significant when planting japonica rice
Summary
Nutrient balance in rice paddy fields can change under different tillage management practices; the extent of the change may differ for various rice varieties. No-till (a method of direct planting crops with minimizing soil disturbance) can reduce soil erosion [2], improve soil aggregation ability [3, 4], retain soil moisture [3, 5], and improve soil structure [2, 6]. It can increase crop yields, reduce economic inputs to the agricultural production systems [7], and achieve significant ecological benefits [3, 8]. Some studies have demonstrated that no-till only increased the nutrient content of the soil in the top 5 cm layer [9, 10].
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