RESUMO
Improving the nutrient content of red soils in southern China is a priority for efficient rice production there. To assess the effectiveness of oilseed rape as green manure for the improvement of soil phosphorus nutrient supply and rice yield in red soil areas, a long-term field plot experiment was conducted comparing two species of rape, Brassica napus (BN) and Brassica juncea (BJ). The effects of returning oilseed rape on soil phosphorus availability, phosphorus absorption, and yield of subsequent rice under rice-green manure rotation mode were analyzed, using data from the seasons of 2020 to 2021. The study found that compared with winter fallow treatment (WT) and no-tillage treatment (NT), the soil available phosphorus content of BN was increased, and that of BJ was significantly increased. The content of water-soluble inorganic phosphorus of BJ increased, and that of BN increased substantially. Compared with the WT, the soil organic matter content and soil total phosphorus content of BN significantly increased, as did the soil available potassium content of BJ, and the soil total phosphorus content of BJ was significantly increased compared with NT. The soil particulate phosphorus content of BJ and BN was significantly increased by 14.00% and 16.00%, respectively. Compared with the WT, the phosphorus activation coefficient of BJ was significantly increased by 11.41%. The rice plant tiller number under the green manure returning treatment was significantly increased by 43.16% compared with the winter fallow treatment. The green manure returning measures increased rice grain yield by promoting rice tiller numbers; BN increased rice grain yield by 9.91% and BJ by 11.68%. Based on these results, returning oilseed rape green manure could augment the phosphorus nutrients of red soil and promote phosphorus availability. Rice-oilseed rape green manure rotation could increase rice grain yield.
RESUMO
The object of the present study was to investigate ten necessary mineral elements in different varieties of rapeseed by ICP-MS. Thirty three samples of double-low (low in both glucosinolates and erucic acid) rapeseed (DLR) and 12 samples of double-high rapeseed (DHR) in the Yangtze River Valley were collected. The results showed that rapeseed contained many kinds of necessary elements, and there was a difference between DLR and DHR The average concentrations of P, K, Ca, Mg, S, Fe, Mn, Cu, Zn and B in DLR were 6.26 mg x g(-1), 10.17 mg x g(-1), 6.75 mg x g(-1), 4.82 mg x g(-1), 4.52 mg x g(-1), 96.20 microg x g(-1), 37.10 microg x g(-1), 3.84 microg x g(-1), 41.61 microg x g(-1) and 12.16 microg x g(-1), respectively, while for the mineral elements in DHR, the average values were 5.97 mg x g(-1), 10. 14 mg x g(-1), 6.31 mg x g(-1), 4.50 mg x g(-1), 9.06 mg x g(-1), 77.03 microg x g(-1), 49.86 microg x g(-1), 3.72 microg x g(-1), 40.58 microg x g(-1) and 11.79 microg x g(-1). The contents of most elements in DLR were higher than those in DHR, such as P, K, Ca, Mg, Fe, Cu, Zn and B. Furthermore, the differences in Ca, Mg and Fe contents between the two varieties were significant. It was concluded that the difference in concentrations of mineral elements can be regarded as a necessary factor for popularizing double-low rapeseed in the Yangtze River Valley.