我国冬油菜典型种植区域土壤养分现状分析

【目的】明确当前生产条件下我国长江流域冬油菜典型种植区域土壤肥力现状,尤其是土壤中微量元素养分含量,以期为冬油菜合理施肥提供参考。【方法】于2018年4—5月在我国长江流域14个省（市）冬油菜典型种植区域采集油菜收获后耕层土壤样品430个,测定土壤基础理化性质（土壤有机质、全氮、速效磷、速效钾和pH）以及中微量元素（有效钙、镁、硫、铁、锰、铜、锌和硼）含量,参考第二次全国土壤普查以及油菜种植土壤速效磷、速效钾和有效硼的分级指标,明确我国长江流域冬油菜主产区油菜种植土壤养分现状,并分析了不同区域（长江上游、中游和下游）、种植制度（水旱轮作油菜和旱地油菜）和产量水平（<2 000 kg·hm ^-2、2 000—3 000 kg·hm ^-2和>3 000 kg·hm ^-2）下油菜种植土壤的养分分布特征。【结果】长江流域冬油菜典型种植区域耕层土壤有机质、全氮、速效磷、速效钾、pH、有效钙、有效镁、有效硫、有效铁、有效锰、有效铜、有效锌和有效硼平均含量分别为25.9 g·kg ^-1、1.47 g·kg ^-1、27.5 mg·kg ^-1、131.1 mg·kg ^-1、6.04、2 436.1 mg·kg ^-1、225.7 mg·kg ^-1、22.6 mg·kg ^-1、212.3 mg·kg ^-1、89.7 mg·kg ^-1、3.84 mg·kg ^-1、4.03 mg·kg ^-1和0.45 mg·kg ^-1。超过2/3田块土壤有机质和全氮含量处于中等及以上;土壤速效磷处于丰富、适宜和缺乏的比例各占1/3;而有63.8%田块土壤速效钾处于缺乏状态。对于土壤中微量元素,土壤有效铁、有效锰和有效铜含量均处于中等及以上,有效钙和有效锌有8.4%和12.2%处于缺乏状态,而土壤有效镁、有效硫和有效硼处于缺乏的比例则分别为24.2%、36.0%和83.5%。长江流域上、中和下游冬油菜典型种植区域土壤养分状况不同,但各区域各养分的分布趋势相同。水旱轮作和旱地油菜种植土壤养分状况存在明显差异,水旱轮作油菜种植土壤有机质、全氮、有效硫、有效铁、有效铜和有效锌含量明显高于旱地油菜。不同产量水平下油菜种植土壤养分特征略有不同,高产（>3 000 kg·hm ^-2）油菜种植田的土壤速效钾、有效钙、有效镁和有效硼含量明显高于低产（<2 000 kg·hm ^-2）油菜田。【结论】整体而言,我国长江流域冬油菜典型种植区域土壤养分含量呈上升的趋势,但土壤速效钾和有效硼缺乏的比例仍较大,有效镁和有效硫成为潜在的限制因子,因此在当前我国长江流域冬油菜生产中,应重视化肥的合理施用,做到稳施氮肥,增施钾肥和硼肥,局部区域如云南西部、广西北部和湖南南部应适当减少磷肥的投入,而在广西北部、湖南南部和江西北部同时应关注硫肥和镁肥的施用。

Soil Nutrient Status of Oilseed Rape Cultivated Soil in Typical Winter Oilseed Rape Production Regions in China

【Objective】 The objective of the study was to investigate the current soil nutrient status of oilseed rape-cultivated soil in typical winter oilseed rape production region in China, especially for soil micronutrients status. It would provide critical reference for optimizing fertilizer strategy of winter oilseed rape. 【Method】 430 soil samples distributed in the typical winter oilseed rape production regions in 14 provinces around the Yangtze River Basin were sampled from April to May, 2018. Soil chemical properties, including soil organic matter, total nitrogen (N), soil available phosphorus (P) and potassium (K), pH, soil available calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn) and boron (B), were determined. Referring to the second national soil survey and the classification index of soil available P, K and B in rapeseed-cultivated soil, soil nutrient status of rapeseed-cultivated soil was clarified, and the soil nutrient characteristics under different regions (upper, middle and lower Yangtze River Basin), planting systems (paddy-oilseed rape and upland-oilseed rape rotation) and seed yield levels (<2 000 kg·hm ^-2, 2 000-3 000 kg·hm ^-2 and >3 000 kg·hm ^-2) were also analyzed. 【Result】 Results showed that the average soil organic matter, total N, soil available P and K, pH, soil available Ca, Mg, S, Fe, Mn, Cu, Zn and B content in the typical winter oilseed rape production region around the Yangtze River Basin were 25.9 g·kg ^-1, 1.47 g·kg ^-1, 27.5 mg·kg ^-1, 131.1 mg·kg ^-1, 6.04, 2 436.1 mg·kg ^-1, 225.7 mg·kg ^-1, 22.6 mg·kg ^-1, 212.3 mg·kg ^-1, 89.7 mg·kg ^-1, 3.84 mg·kg ^-1, 4.03 mg·kg ^-1and 0.45 mg·kg ^-1, respectively. More than two-thirds of soil organic matter and total N content belonged to the medium class or above. For soil available P content, the proportion of the rich, medium and deficient class accounted for one-third, respectively. While 63.8% of soil available K content was deficient. For soil available Fe, Mn and Cu, all soils belonged to the medium class or above. Only about 8.4% and 12.2% of soils were soil deficient Ca and Zn soil, respectively. The proportions of deficient Mg, S and B soils accounted for 24.2%, 36.0% and 83.5%, respectively. Soil nutrient contents in the upper, middle and lower Yangtze River Basin were different, however, the distributions of soil nutrient status in different regions were similar. There were significant differences on soil nutrient content between paddy and upland soils. The rapeseed-planting soils in paddy-oilseed rape rotation showed significant higher soil organic matter, total N, soil available S, Fe and Zn content. Soil nutrient characteristics under different seed yield levels were slight different. Soils with high rapeseed yield (>3 000 kg·hm ^-2) revealed higher soil available K, Ca, Mg and B content compared with the soils with low rapeseed yield (<2 000 kg·hm ^-2). 【Conclusion】 Soil nutrients content in the typical winter oilseed rape planting area around the Yangtze River Basin was increasing, nevertheless, the percentages of deficient K and B soils were still huge, and soil available Mg and S were gradually becoming the potential limiting factors of winter oilseed rape. Therefore, in the current production of winter oilseed rape in the Yangtze River Basin, we should pay more attention to the rational application of chemical fertilizers, applying N fertilizer continuously and reasonably, increasing K and B fertilize application, reducing P fertilization rate in western Yunnan, northern Guangxi and southern Hunan depending on soil available P content, and focusing on the application of S and Mg fertilizer in northern Guangxi, southern Hunan, and northern Jiangxi.