黄土高原新造耕地施用羧甲基纤维素钾的土壤效应

  目的  基于黄土高原新造耕地土壤质量改良需求，开展以羧甲基纤维素钾（CMC-K）为土壤改良剂的田间定位试验研究，为新造耕地土壤水分保持与养分改良提供依据。  方法  设置CK（0 kg hm?2）、T1（100 kg hm?2）、T2（500 kg hm?2）、T3（1000 kg hm?2）和T4（2000 kg hm?2）5个处理，对不同处理的新造耕地土壤水分、电导率与养分进行了测定与分析。  结果  新造耕地施用CMC-K土壤含水量提高14.6%～121.7%，在谷子生长季前期（6月和7月）和后期（10月）土壤保水功效较大。在CMC-K较高施用量（1000 ~ 2000 kg hm?2）情况下，谷子生长季前期（6月）土壤电导率提高了37.3% ~ 73.4%；全部处理在谷子生长季后期（10月）的土壤电导率显著降低，降低幅度达19.2% ~ 21.8%；谷子生长季的土壤电导率呈现降低趋势。施用CMC-K能够提高土壤硝态氮9.6% ~ 46.5%、速效磷21.9% ~ 207.9%和速效钾13.2% ~ 95.9%，对土壤pH基本没有影响。施用CMC-K谷子产量提高了6.2% ~ 19.2%。  结论  施用CMC-K能够保持土壤水分，促进养分吸收利用，提高谷子产量，可以作为黄土高原新造耕地土壤改良剂使用，推荐施用量约100 kg hm?2。

Effects of Application of Potassium Carboxymethyl Cellulose on Soil Water and Nutrients in Newly Cultivated Farmland

  Objective  Based on the requirement of soil water and nutrient improvement of newly cultivated farmland of Loess Plateau in Yanan, Shaanxi Province, potassium carboxymethyl cellulose (CMC-K) was acted as a soil amendment.   Method  The field experiment was conducted with 5 treatments ( CK, 0 kg hm?2; T1, 100 kg hm?2; T2, 500 kg hm?2; T3, 1000 kg hm?2; T4, 2000 kg hm?2) to research the changes in soil water, soil electric conductivity and soil nutrients.  Result  CMC-K application improved soil water content 14.6%-121.7% in newly cultivated farmland, the efficacy of CMC-K application was better in early (June and July) and end-stage (October) of millet growing season than those in the middle stage (August and September). The large CMC-K application amounts (1000-2000 kg hm?2) could improve significantly soil electric conductivity by 37.3%-73.4% in early (June) of millet growing season, and soil electric conductivities of all treatments were decreased significantly by 19.2%-21.8% in end (October) of millet growing season. Soil electric conductivities presented decreasing trend in the millet growing season. CMC-K application had no effects on soil total nitrogen, total phosphorus, total potassium, and pH, but enhanced soil nitrate (9.6%-46.5%), available phosphorus (21.9%-207.9%), and available potassium (13.2%-95.9%). CMC-K application could increase millet yield by 6.2%-19.2%.  Conclusion  CMC-K application can hold soil water, promote soil nutrient absorption and raise millet yield in newly cultivated farmland in Loess Plateau, which may act as a soil amendment and the recommended application rate is 100 kg hm?2.