青海省春油菜区土壤养分状况及施肥策略

【目的】海拔高度、成土母质、气候条件、种植品种、耕作方式和施肥水平等因素对农田土壤肥力产生深刻影响。调查明确青海省春油菜区土壤养分的空间分布现状,有助于制定合理的施肥策略和实现该地区春油菜高产优质以及农业的可持续发展。【方法】2015年在青海省东部的湟中、大通和互助三个春油菜主产县,依据各乡镇油菜种植面积大小,共采集了103个耕层土壤样品。测定土壤主要养分含量,并结合ArcGIS中的Kriging插值法研究春油菜田土壤肥力现状及其空间分布特征。【结果】土壤各养分平均含量分别为有机质26.81 g/kg (中等)、全氮1.97 g/kg (丰富)、速效磷19.03 mg/kg (中等)、速效钾164.27 mg/kg (丰富)、有效铁12.02mg/kg (丰富)、有效锰6.43 mg/kg (中等)、有效铜0.70 mg/kg (中等)、有效锌1.81 mg/kg (中等)、有效硼0.27mg/kg (缺乏)。三县土壤全氮和速效磷含量达到中等水平以上的比例分别为94%和91%。速效钾和有效锌含量区域差异较大,速效钾缺乏及以下比例有23.0%,主要分布在湟中和互助县,有效锌缺乏及以下比例有36.9%,主要分布在互助县;有效硼缺乏及以下比例高达93.2%,主要分布在互助和大通县。【结论】青海省春油菜土壤氮磷钾养分含量整体偏高,相应化肥减量空间较大。大通、互助两县应合理减施氮肥;湟中、大通两县应降低磷肥施用量;针对湟中和互助县的速效钾含量缺乏地区应适当增施钾肥。土壤有效硼除湟中县的部分地区外均缺乏严重,有效锌含量缺乏的土壤主要分布在互助县,针对以上区域应合理增施硼肥和锌肥,防止作物因缺素而限制产量和品质的提高。养分的平衡供应将有利于提高肥料利用率,实现春油菜产业的可持续发展。

Status of soil nutrients of spring rapeseed planting area and fertilization strategy in eastern Qinghai Province

Objectives Altitude, parent material, climate, crop cultivar, tillage system and fertilization rate have strong impacts on fertility of cropland. This survey has clarified the current contents of soil nutrients in spring rapeseed planting area of Qinghai Province, which will be helpful to establish proper fertilization strategy for high yield and quality rapeseed production and sustainable development of agriculture. Methods There are three major counties for spring rapeseed production, i.e. Huangzhong, Datong and Huzhu counties of eastern Qinghai Province. In total, 103 soil samples were collected from the plough layers of farmlands for spring rapeseed production in 2015, and the primary soil nutrient contents were determined. In conjunction with ArcGIS and Kriging interpolation, the current soil fertility of spring rapeseed planting fields and its spatial distribution characteristics were studied. Results The average contents and levels of soil nutrients were: soil organic matter 26.81 g/kg (moderate), total N 1.97 g/kg (rich), available P 19.03 mg/kg (moderate), available K 164.27 mg/kg (rich), available Fe 12.02 mg/kg (rich), available Mn 6.43 mg/kg (moderate), available Cu 0.70 mg/kg (moderate), available Zn 1.81 mg/kg (moderate) and available B 0.27 mg/kg (deficient). Among the three counties, 94% of soil total N and 91% of soil available P contents were above the moderate levels. The available K and Zn contents were greatly different from each other. 23.0% of the soil was deficient in available K, and the K deficient soil was mainly distributed in Huangzhong and Huzhu. Zn deficient area was 36.9%, which was mainly distributed in Huzhu. As high as 93.2% of the soil was deficient in B and mainly distributed in Huzhu and Datong. Conclusions The spring rapeseed fields were generally high in soil N, P and K contents, indicating potential for the reduction of NPK fertilizers. In details, nitrogen fertilizer rate should be reduced properly in Datong and Huzhu, and phosphorus fertilizer rates should be reduced in Huangzhong and Datong. Potassium fertilizers should be applied in low K fields in Huangzhong and Huzhu. As the large areas of severe B deficiency in the three counties and the deficiency of available Zn in Huzhu County, B and Zn fertilizers should be applied properly to avoid the decrease of crop yield and quality due to the short supply of important plant nutrients. The balanced supply of nutrients will help to improve the fertilization efficiency and realize the goal of sustainable development of the spring rapeseed industry.