• ISSN 1008-505X
  • CN 11-3996/S
吴驳, 吴发启, 佟小刚, 宋敏敏, 侯雷. 近40年泥河沟流域耕地土壤磷素含量的时空变化[J]. 植物营养与肥料学报, 2019, 25(5): 851-858. DOI: 10.11674/zwyf.18127
引用本文: 吴驳, 吴发启, 佟小刚, 宋敏敏, 侯雷. 近40年泥河沟流域耕地土壤磷素含量的时空变化[J]. 植物营养与肥料学报, 2019, 25(5): 851-858. DOI: 10.11674/zwyf.18127
WU Bo, WU Fa-qi, TONG Xiao-gang, SONG Min-min, HOU Lei. Spatio-temporal variability of phosphorus content in cultivated soils in Nihegou watershed in recent 40 years[J]. Journal of Plant Nutrition and Fertilizers, 2019, 25(5): 851-858. DOI: 10.11674/zwyf.18127
Citation: WU Bo, WU Fa-qi, TONG Xiao-gang, SONG Min-min, HOU Lei. Spatio-temporal variability of phosphorus content in cultivated soils in Nihegou watershed in recent 40 years[J]. Journal of Plant Nutrition and Fertilizers, 2019, 25(5): 851-858. DOI: 10.11674/zwyf.18127

近40年泥河沟流域耕地土壤磷素含量的时空变化

Spatio-temporal variability of phosphorus content in cultivated soils in Nihegou watershed in recent 40 years

  • 摘要:
    目的 磷是限制黄土高原地区农业生产的重要元素,研究黄土高原已治理小流域耕地土壤磷素含量的时空变化对该区耕地的评价与管理有着重要的指导意义。
    方法 在实地调查研究的基础上,通过细致试验、微观分析和流域信息反馈检验,在不同时间、空间尺度上,计算整理归纳了近40年泥河沟流域耕地土壤磷素含量的变异性,并对引起变异的有关因素进行了分析。
    结果 从时间上看,近40年泥河沟流域耕地土壤全磷含量呈现加速下降趋势,有效磷含量呈现先上升后下降的波动变化。土壤全磷含量随时间的变异与作物产量和施磷量的改变有关,1980—1998年耕地施用农家肥和磷肥较多,土壤磷的“输入”与“输出”较平衡,土壤全磷含量稳定在1.31~1.34 g/kg之间;1998—2015年农家肥和磷肥投入减少,氮肥和复合肥投入增多,农作物产量持续增加,土壤全磷含量降低了27.1%。土壤有效磷含量的时间变异与施肥结构和速效磷肥施用量的改变有关,1980—2004年耕地速效磷肥的投入量增加了120 kg/hm2,土壤有效磷含量随之提高了2.6倍;2004—2015年由于施肥结构改变,速效磷肥的投入量减少,土壤碱性增强,土壤有效磷含量降低了24.7%。从空间上看,土壤磷素含量的空间变异主要受土壤侵蚀和土地管理的综合影响。均整坡耕地上土壤磷素含量呈现坡上 < 坡下,全坡面断面上呈现塬地 > 塬畔地 > 沟底地 > 沟坡地,全流域呈现平耕地 > 坡耕地 > 新修梯田。整坡耕地上土壤侵蚀使径流挟带泥沙和养分顺坡单向迁移,因为有效磷的迁移性比全磷强,所以差异性为有效磷 > 全磷;全坡面断面上靠近分水岭的塬地由于靠近居民区管理较为精细,土壤培肥程度高,土壤有效磷含量比其他位置耕地高出1倍以上;通过治理,全流域耕地的地形条件差异逐渐缩小,梯田面积由1980年的100 hm2增加至现在的250 hm2,坡耕地面积由1980年的250 hm2降低到现在的50 hm2;新修梯田由于受到土壤扰动的影响,其土壤磷素含量接近母质,比老梯田和坡耕地低。
    结论 流域经历近20年的治理和10年以上的社会化自由管理,耕地土壤全磷含量呈现降低的趋势,土壤有效磷含量依然主要依赖于速效磷肥的补给,这将是流域农业发展的重大隐患。随着农村劳动力的季节性流动,耕地利用管理需要在省工省时的基础上得到优化,调整施肥结构,实现集约化经营将是今后该区农业发展的重要方向。

     

    Abstract:
    Objectives Phosphorus is one of the limiting factors in the agricultural production of the Loess Plateau. It is of great significance to study the temporal and spatial variation of soil phosphorus content in the cultivated land of harnessed small watershed for the evaluation and management of cultivated land in this area.
    Methods From 1980 to 2005, five field surveys had been carried out and total of 457 soil samples were collected at different time and space scales within Nihegou watershed, the soil total phosphorus and Olsen-P contents were analyzed. The variation of soil P was calculated and summarized by detailed experiments, micro-analysis and information feedback test, and the causes of the variation were discussed.
    Results As viewed from the time, the soil total-P content of cultivated land showed an accelerated decline in the past 40 years, and the soil Olsen-P content showed a fluctuating change of first rising and then decreasing. The time variation of total-P content in soil was related to the change of crop yield and phosphorus application rate. Because farm manure and phosphorus fertilizer were more applied to cultivated land from 1980 to 1998, the “input” and “output” of phosphorus in all soils were more balanced, and soil total-P content was stable between 1.31 g/kg and 1.34 g/kg. The time variation of soil Olsen-P content was related to the change of fertilizer structure and available phosphorus fertilizer application rate. As the input of available phosphorus fertilizer per hectare in cultivated land was increased by 120 kg from 1980 to 2004, the soil Olsen-P content was increased by 2.6 times. From 2004 to 2015, due to the promotion of compound fertilizer, the application rate of phosphate fertilizer decreased, and the soil available phosphorus content was decreased by 24.7%. As viewed from the space, the spatial variability of soil phosphorus cont was mainly affected by soil erosion and land management. The content of phosphorus in sloping farmland was higher than that on slope. The whole slope surface shows flat land > gully upper land > gully bottom land > gully slope land. Because soil erosion on uniform sloping farmland causes one-way transport of sediment and nutrients along slopes, and the mobility of Olsen-P was higher than that of total-P. The land close to the watershed on the whole slope section was managed more carefully because of its close proximity to the residential area, and the soil fertility was high. The soil Olsen-P content was more than one times higher than that in other cultivated land. Through harnessing, the topographic conditions of cultivated land in the whole basin gradually narrowed, the terrace area increased from 100 hm2 in 1980 to 250 hm2 at present, and the slope farmland area decreased from 250 hm2 in 1980 to 50 hm2 at present. Under the influence of soil disturbance, the phosphorus content in newly constructed terraces was close to parent material and lower than that in old terraces and sloping fields.
    Conclusions After nearly 20 years of harnessing and more than 10 years of socialized and free management, the soil total-P content shows a downward trend. The soil Olsen-P content mainly depends on the supply of available phosphorus fertilizer, which will be a major hidden danger for the development of agriculture in the basin. With the seasonal flow of rural labor force, cultivated land management needs to be optimized on the basis of saving labor and time. Adjusting fertilizer structure and realizing intensive management will be an important direction for agricultural development in the future.

     

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