土壤养分状况系统研究法在土壤肥力研究及测土施肥中的应用

SYSTEMATIC APPROACH FOR SOIL NUTRIENT STATUS EVALUATION AND ITS USE IN FERTILIZER RECOMMENDATION

土壤养分状况系统研究法应用美国国际农化中心的ASI联合浸提液(0.25mol/L NaHCO_3-0.01mol/L EDTA-0.01mol/L NH_4F)测定土壤中11种大、中、微量元素含量,结合土壤对营养元素的吸附研究和盆栽试验,判断土壤中存在的和潜在的养分限制因子,用以指导田间试验和施肥推荐。在全围17个省(市、自治区)范围内选取了140个土壤样品,应用该方法对土壤养分状况进行了研究。盆栽试验结果表明,土壤中氮、磷、钾、锌、硫、铜、硼、锰、钼、镁、钙和铁成为限制因子的土壤分别为137、126、84、68、45、37、36、34、28、25、20和17个。应用Cate和Nelson的方法估计出11种元素(钼除外)测定值在盆栽条件下的临界值。 应用在原取土地块安排的田间试验的资料估计出大田条件下应用ASI联合浸提液测定的土壤磷、钾含量的临界值分别为15mg/L和90mg/L。应用河北省玉田县试验和示范资料建立的计算机测土施肥模型综合考虑了土壤中各种营养元素的综合平衡和土壤对磷、钾的吸附固定能力。

A systematic approach technique has been introduced from Agro Service International (ASI), and further modified and developed to evaluate soil nutrients status in China. The systematic approach consists of 1) soil testing for availability of 11 nutrients by using a multi-elements extraction solution (ASI solution: 0. 25mol/L NaHCO3 -0.01mol/L EDTA-0.01mol/L NH4F); 2) determination of adsorption capacity of the soil for P. K, S, B, Mn, Zn and Cu: and 3) pot experiments to estimate the existing or potentially existing nutrient deficiency; 4) field trials to verify the finding in the laboratory and pot experiments. The technique has been used for 140 soils taken from 17 provinces of China. Soil testing and pot experiments indicated that, among the 140 soils, the number of soils showed deficient in N, P, K, Zn, S, Cu. B, Mn, Mo, Mg, Ca and Fe were 137, 126, 84, 68, 45, 37, 36, 34, 28. 25, 20, and 17, respectively. By using the Cate-Nelson method, the adequate level of each nutrient under pot culture condition was estimated, which was in good agreement with that recommended by ASI. Field trials were designed at the sites where soil samples were taken, based on the findings from the laboratory and pot experiments. Critical levels of soil P and K determined by using the ASI multi-nutrients extraction solution, were also estimated by using the Cate-Nelson method, and data from the field trials. The estimated critical level for P and K under field condition were 15mg/L and 90mg/L soil, respectively. The systematic approach was used in Yutian county of Hebei province in a large scale for soil nutrients status evaluation. Based on the results of the soil testing, adsorption study, pot experiments, field experiments and field demonstration plots, a computer program was developed and used in a large scale for balanced fertilizer recommendation for major crops in the county.