Excessive application of phosphorus fertilizer leads to high soil available phosphorus content but low phosphorus use efficiency in the main production areas of spring rape in eastern Qinghai. Understanding the effects of phosphorous application rates on the growth, phosphorus absorption, soil phosphorus balance in the field of spring rape could improve nutrient management of spring rape, and benefit for the sustainable development of agriculture in Qinghai-Tibet Plateau. A field experiment was carried out in Huzhu County of Qinghai Province from 2017 to 2018. We mea-sured seed yield, phosphorus uptake and oil content of spring rape under five phosphorous fertilizer rates (0, 30, 60, 90 and 120 kg P2O5·hm-2). In 2017, the seed yield and oil production of spring rape with the rate of 60 kg·hm-2 were significantly higher than that of no phosphorus fertilizer treatment. In contrast, seed yield and oil production did not increase when the phosphorus rate exceeded 60 kg·hm-2 in 2017. Phosphorus rate did not affect seed yield, phosphorus accumulation, and oil production of spring rape in 2018. The phosphorus use efficiency was low in both years, with a mean value of 6.7%. Phosphorus fertilizer application caused phosphorus surplus in soils, which was low when the application rate was less than 60 kg·hm-2. Our results suggest that the rate of 60 kg·hm-2 is suitable for spring rape production in the eastern Qinghai Province.
青海省东部春油菜主产区的土壤速效磷含量高、磷肥施用量大、磷肥利用率低。研究不同施磷量对春油菜的生长、磷素吸收和利用、土壤磷素平衡的影响,可为该地区春油菜田养分高效管理提供科学依据,对保障青藏高原农业可持续发展具有重要意义。本研究于2017和2018年在青海省互助县开展了田间试验,设置0、30、60、90、120 kg P2O5·hm-2 5个磷肥施用量,测定了不同处理春油菜的产量、磷素吸收与利用、籽粒含油率等。结果表明: 2017年施磷量60 kg·hm-2处理的油菜籽粒产量、成熟期地上部磷素累积量和产油量均显著高于不施磷处理,但施磷量超过60 kg·hm-2后,籽粒产量和产油量不再增加;2018年施磷量对春油菜籽粒产量、成熟期地上部磷素累积量和产油量均无显著影响。两年度的磷肥表观利用率均很低,平均为6.7%。施用磷肥条件下土壤均有不同程度的磷素盈余,施磷量低于60 kg·hm-2时盈余量较低。综合考虑春油菜产量、产油量、磷肥表观利用率和土壤磷素表观平衡,在青海省东部春油菜区,推荐施磷量为60 kg·hm-2。.
Keywords: phosphorus application rate; soil phosphorus balance; spring rape.