【作者】 王旭刚；

【导师】 郝明德；

【作者基本信息】 西北农林科技大学 ， 土壤学， 2004， 硕士

【摘要】 在农田生态系统中，土壤的养分平衡是作物稳产、高产的基础。农田养分平衡研究有助于从宏观上观察肥料投入过程中农田作物消耗和土壤肥力等变化。而且，养分平衡和循环有一定的地理、时空差异性，黄土高原又有其自身的特殊性，在黄土高原进行养分平衡研究有其实际意义。 本文利用设在黄土高原旱地上的长期轮作与施肥试验，主要研究了黄土高原农田生态系统养分的降水带入、作物地上部分的氨挥发损失和作物的养分支出，并进行了 N、P、K 养分平衡评价。 降水中的 N 输入土壤是黄土高原旱塬区农田的一种重要 N 素输入方式，年输入量6.72-10.80 kg/hm2，主要发生在 6-9 月，占全年输入量的 57.8%。降水输入土壤的 N、K量与降水量呈明显的相关关系。 氨挥发损失是旱地农田 N 素损失的重要途径之一。长期施用有机肥可显著降低 N的氨挥发损失，在试验的温度范围内氨挥发损失随温度升高而增大。在营养生长期，小麦与苜蓿地上部分的氨挥发损失速率较低且没有明显差异，但进入生殖生长期成倍增加，苜蓿的氨挥发损失高于小麦 65%左右。氨挥发的年损失量在 3.99-9.37 kgN/hm2之间。 合理的肥料配施可提高肥料的利用率，降低作物的草籽比，促进养分向籽粒产量转移。同种作物不同施肥水平下的养分吸收量不同，在 72.44 kgN/hm2和 46.90 kgP/hm2时可以获得最小的 N 的养分消耗量：3.77 kg/100kg 籽粒产量，在 124.97 kgN/hm2和 29.61kgP/hm2 时可以获得最小的 P 养分消耗量：0.61 kg/100kg 籽粒产量。 施用化肥对土壤有机 C 含量影响不显著，有机无机肥配施使土壤有机 C 含量大幅度的提高。相同施肥条件下苜蓿对有机 C 与全 N 含量的提高幅度大于小麦。种植作物可提高土壤供氮能力，苜蓿连作、小麦连作和粮饲豆轮作土壤全氮和碱解氮含量分别比裸地增加 4.21%-36.50%和 7.61%-66.91%，其中以种植苜蓿提高幅度最大，是分别是裸地的1.36 和 1.67 倍。 在轮作系统中引入豆科作物后，土壤有机 C、全 N、有效氮含量显著增加，但全磷和有效磷却有所降低。随着苜蓿生长年限的增加，耕层全 N、有效氮含量均有不同程度的提高。长期施用有机肥能显著提高土壤耕层养分含量，主要是因为肥料带入土壤的养分没有全部被作物携走而在土壤中的累积。施肥量在 N 51.89kg/hm2、P 11.90kg/hm2左右可满足作物的养分需求，又不使养分在土壤中累积。 对本区的养分状况进行评价的结果表明，本区土壤中 N 每年盈余 21.47-32.48%，P盈余 44.54-74.56%，不施钾肥钾素亏缺 2.45-6.29kg/hm2,所以在肥料用量上，应适当控N、减 P、增 K。更多还原

【Abstract】 In farmland ecosystem, the balance of soil nutrients is the base of stabilizing andincreasing yield of crop. Research of nutrients balance in farmland can help looking into thevariety and problem possibly appeared in process of farmland nutrients degenerate andregenerate from macro angle. Furthermore, there has geography space-time otherness in thebalance and circulation of farmland nutrients geography space-time otherness, and the loessplateau has its own particularity. Therefore, doing research of the nutrient balance in the loessplateau has its practical signification. Using the long-term rotation and fertilization experiment that disposed in dry land on theloess plateau, the paper has studied nutrients in rainfall import to farmland ecosystem andAmmonia volatilization losses and nutrients disbursal of crop, also estimated the balance ofnutrients in farmland soil. N input with rainfall is an important method of N input in dry land on the loess plateau,its amount in a year is 6.72-10.80 kg/hm2, and it mostly happened between June andSeptember. Furthermore, there has distinctness correlativity between the amount of N、P、Kin rainfall and annual precipitation in this area. Ammonia volatilization losses of N are one of the important losses methods in dry land.Long-term application of organic manure can evidently decrease the Ammonia volatilizationlosses. Ammonia volatilization losses increased adapt to the hoist of temperature inexamination range. In period of nourishment growth, Ammonia volatilization losses velocityis very small and there is no evidently difference between winter wheat and alfalfa. But inprocreation growth period, it increased geminately. The amount of ammonia volatilizationlosses in a year is about 3.99-9.37kgN/hm2. Proportion fertilization in reason can increase utilization ratio of fertilizer, decrease theratio of stalk/seed, and promote nutrients moving to economic yield. The same crop hasdifferent nutrients wastage under different fertilization, N wastage has minimum of3.77kgN/100kg economic yield under fertilization of 72.44kgN/hm2 and 46.90kgP/hm2. Pwastage has minimum of 0.61 kgP/100kg under fertilization of 124.97kgN/hm2and29.61kgP/hm2. With the increasing of fixed number of year, nutrients content in wheat stalkand seed decreased, that in alfalfa increased. Fertilization has less effect on the content of soil organic C, organic fertilizer appliedwith mineral fertilizer can increased soil organic C content evidently. Crop cultivation canincrease soil N supply ability, increase range is between 6.88% and 36.58%, the most of itis alfalfa, and its increase amount is 1.37 times of bareness. Content of soil organic C 、total<WP=7>iii AbstractN and available N increased evidently, but total P and available P decreased in some degree,when leguminous plants induct into rotate system. Furthermore the content of total N andavailable N in plough layer increasing with the fixed number of year. Long-term fertilizationcan increase soil nutrients content evidently is because of crop can’t uptake all the nutrients infertilization and the nutrients cumulated in soil. It can supply crop nutrients requirement andcan’t cause nutrients cumulated in soil with the fertilization of N 51.89 kg/hm2 、 P11.90kg/hm2. Estimate nutrients status in this area, the result showed that, there is surplus 21.47-32.48% of fertilizer N and 44.54-74.56% of fertilizer P. K has 2.45-6.29 kg/hm2·a to the badlack of fertilizer K. Therefore, it should stabilize N 、 K fertilization and decrease Pfertilization.更多还原