土壤磷素环境阈值与农学阈值研究

发布时间：2018-05-05 17:49

本文选题：土壤磷素 + 淋溶阈值　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：磷是作物必需的大量元素,土壤磷素水平和施磷量是保障农作物高产和影响农田磷素流失的主要因素。本研究选择全国分布面积较广的18种土壤,应用室内模拟结合数学模型,研究了不同类型土壤磷素淋溶的环境阈值,结合理化性质探讨了影响磷素淋溶风险的主要影响因子;以盆栽试验为基础,根据作物产量对土壤有效磷的相应关系研究了不同土壤冬小麦夏玉米达到最佳产量时的农学阈值;以“国家黄土肥力与肥料效益监测基地”24年长期肥料定位试验为基础,利用长期试验积累数据并结合相关土壤分析,探讨X土上有效磷对冬小麦和夏玉米产量的影响、土壤有效磷随全磷累积的变化规律、土壤磷的淋溶阈值;结果可为土壤磷素淋溶风险评价和预测、磷肥的合理施用和优化土壤磷素管理提供科学依据。主要结论如下:(1)X土区冬小麦高产时土壤有效磷临界值为26.2 mg·kg-1,夏玉米为13.9 mg·kg-1。土壤有效磷随全磷的增加存在明显的临界点,当全磷含量为1.15 g·kg-1时,有效磷含量为34.8 mg·kg-1,高于此值后有效磷随全磷快速增加。土壤有效磷含量大于39.3 mg·kg-1时,磷素淋溶风险增大。在无轮作体系的情况下,当土壤有效磷含量分别为25、25~40和40 mg·kg-1时,冬小麦施磷量分别为80~95、60~80和10~15 kgP2O5·hm-2;当土壤有效磷15、15~40和40 mg·kg-1时,夏玉米施磷量分别为70~85、55~70和10~15kgP2O5·hm-2。在冬小麦-夏玉米轮作体系下,当土壤有效磷含量分别为15、15~25、25~40和40 mg·kg-1时,冬小麦施磷量分别为100~120、90~100、80~90和15~20 kgP2O5·hm-2;夏玉米施磷量分别为50~60、45~50、25~40和5~10 kgP2O5·hm-2。(2)18种供试土壤P淋失临界点处Olsen-P含量为14.9~119.2 mg·kg-1,CaCl2-P含量范围为0.11~2.26 mg·kg-1。不同土壤磷素淋失阈值差异很大,与土壤pH、交换性钙含量及呈极显著负相关而与活性铁铝含量、粘粒含量及初始有效磷水平呈极显著正相关(p0.01)。以土壤pH、有机碳、活性铝、交换性钙、交换性镁、碳酸盐、粘粒、初始Olsen-P和初始CaCl2-P含量为影响因素建立的数学模型,可为综合评价土壤土壤理化性质对土壤磷素淋溶风险的影响提供参考。(3)由8种土壤盆栽实验得出,冬小麦土壤有效磷农学阈值为13.1~26.2 mg·kg-1,夏玉米农学阈值为9.78~16.0 mg·kg-1。有效磷含量为12 mg·kg-1可作为潮土农学阈值。有效磷20mg·kg-1可作为X土、黄棕壤、红壤和水稻土的农学阈值。(4)供试土壤环境阈值约为农学阈值1~4倍,不同土壤类型保障作物高产和水环境安全的有效磷含量范围差异较大。小麦玉米轮作模式下,对于潮土、灰漠土、灌淤土等容易发生磷素淋溶的碱性土壤,有效磷含量应控制在12~20mg·kg-1范围内。对于红壤等酸性土壤,有效磷含量应控制在20~40mg·kg-1。对于X土等石灰性土壤,有效磷含量应控制在20~40mg·kg-1,但合理的施磷量应低于红壤等酸性土壤。
[Abstract]:Phosphorus is a necessary element in crops. Soil phosphorus level and phosphorus application amount are the main factors to ensure high yield of crops and to affect the loss of phosphorus in farmland. In this study, the environmental threshold of phosphorus leaching in different types of soils was studied by using indoor simulation and mathematical model, and the main influencing factors affecting phosphorus leaching risk were discussed in combination with physical and chemical properties. Based on pot experiment, the agronomic threshold of winter wheat and summer maize in different soils was studied according to the relationship between crop yield and soil available phosphorus. Based on the long-term fertilizer location test of "National Loess Fertility and Fertilizer benefit Monitoring Base" for 24 years, the effects of available phosphorus on winter wheat and summer maize yield were studied by using long-term experiment data and soil analysis. The change of soil available phosphorus with the accumulation of total phosphorus and the leaching threshold of soil phosphorus can provide scientific basis for evaluating and predicting the risk of soil phosphorus leaching, rational application of phosphorus fertilizer and optimization of soil phosphorus management. The main conclusions are as follows: the critical value of available phosphorus in winter wheat is 26.2 mg 路kg ~ (-1) and 13.9 mg / kg ~ (-1) in summer maize and 26.2 mg 路kg ~ (-1) in winter wheat. When the total phosphorus content was 1.15 g / kg-1, the available phosphorus content was 34.8 mg / kg ~ (-1). When the total phosphorus content was 1. 15 g / kg-1, the effective phosphorus content was 34.8 mg / kg ~ (-1). The risk of phosphorus leaching increased when the available phosphorus content was more than 39.3 mg kg-1. Under the condition of no rotation system, when the available phosphorus content in soil was 25 ~ 25N ~ 40 and 40 mg / kg-1, the P application rates of winter wheat were 80 ~ 95 ~ 5 ~ 60 ~ (-80) and 1015 kgP2O5 ~ (-2) h ~ (-2), respectively, and that of summer maize were 70855 ~ 55 ~ 70 and 10~15kgP2O5 h ~ (-2) when soil phosphorus was 15 ~ 1540 mg / h ~ (-1) and 40 mg / m ~ (-1) kg-1, respectively. Under the winter wheat-summer maize rotation system, when the available phosphorus content of soil was 15 ~ 15 ~ 15 ~ 25 ~ 25 ~ 2540 mg / kg-1 and 40 mg / kg-1, respectively, The amount of phosphorus applied in winter wheat was 100 ~ (120) ~ (90) ~ (90) ~ 100 ~ (-1) kgP2O5 ~ (-1) h ~ (-2) and that of summer maize was 50 ~ (60) ~ (45) ~ 50 ~ (25) C ~ (-40) and 5 ~ (10) kgP2O5 hm-2.(2)18, respectively. The content of Olsen-P at the critical point of P leaching was 14.9 ~ 119.2 mg 路kg ~ (-1) CaCl _ (2-P) in the soil, the range of which was 0.11 ~ 2.26 mg 路kg ~ (-1). There were significant differences in P leaching threshold between different soils, which were negatively correlated with soil pH, exchangeable calcium content and active iron and aluminum content, clay content and initial available phosphorus level, but positively correlated with soil pH, exchangeable calcium content and initial available phosphorus level. The mathematical model was established with soil pH, organic carbon, active aluminum, exchangeable calcium, exchangeable magnesium, carbonate, clay, initial Olsen-P and initial CaCl2-P as the influencing factors. The results showed that the threshold of available phosphorus in winter wheat soil was 13.1 ~ 26.2 mg 路kg ~ (-1) and that in summer maize was 9.78 ~ (16.0 mg 路kg ~ (-1). The available phosphorus content of 12 mg kg-1 can be used as the agronomic threshold. Available phosphorus 20mg kg-1 can be used as the agronomic threshold of X soil, yellow brown soil, red soil and paddy soil. The environmental threshold of tested soil is about 1 ~ 4 times that of agronomic threshold. The range of available phosphorus content in different soil types to ensure high yield of crops and safety of water environment is quite different. Under the wheat-maize rotation model, the available phosphorus content in alkaline soils, such as aquic soil, grey desert soil and irrigated silt soil, which is prone to phosphorus leaching, should be controlled within the range of 12~20mg kg-1. For acidic soils such as red soil, the available phosphorus content should be controlled at 20~40mg kg-1. For calcareous soils such as X soil, the content of available phosphorus should be controlled in 20~40mg kg-1, but the reasonable amount of phosphorus application should be lower than that in acidic soils such as red soil.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S153;X144

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