南阳植烟土壤养分时空演变特征及肥力评价

采用定点取样方法,分别于2000年和2020年采集南阳市代表性植烟土壤样品,进行土壤养分时空变化特征分析和肥力评价。结果显示,与2000年相比,2020年全市植烟土壤pH均值下降了1.26,速效磷和水溶性氯平均含量分别下降了11.39%和36.47%,有机质和碱解氮平均含量分别增加了19.69%和90.92%,速效钾平均含量无显著变化。经过20年持续利用,南阳植烟土壤肥力显著提升,肥力指数由0.46提高至0.57,适宜性指数等级由以V级为主提升至以III级为主,中等及以上区域达到植烟总面积的70.70%。2020年全市分别有55.87%、42.21%和63.09%的植烟土壤有机质、有效磷和速效钾含量低于适宜范围,52.13%的土壤水溶性氯含量高于阈值。根据土壤肥力时空演变特征和当前肥力水平,建议分区采用“补磷钾、增施有机肥、降氯”措施,改善土壤质量状况。

Spatial-Temporal Variability of Soil Nutrients and Assessment of Soil Fertility in Nanyang Tobacco Planting Areas

The representative tobacco planting soil samples of Nanyang were separately collected in 2000 and 2020 by the fixed-point sampling method, and were used for analyzing the temporal and spatial variation characteristics of soil nutrients and evaluating soil fertility. The results showed that, the pH value of the tobacco soil decreased by an average of 1.26 units from 2000 to 2020, and the average content of available phosphorus and water-soluble chlorine decreased by 11.39% and 36.47%, respectively; Meanwhile, the average organic matter and alkali-hydrolyzable nitrogen increased by 19.69% and 90.92%, respectively. However, the average content of available potassium remained the same level. After 20 years’ continuous utilization, the soil fertility of tobacco planting fields in Nanyang had been significantly improved, the fertility index of tobacco-planting soil increased from 0.46 to 0.57 and the suitability index level increased from V to III. Moreover the medium and higher grade tobacco planting soil had occupied 70.70% of the total area. In 2020, soil organic matter, available phosphorus and available potassium content of tobacco planting fields in the city were all lower than the appropriate range, respectively less than 55.87%, 42.21% and 63.09%, and 52.13% of the soil water-soluble chlorine content was higher than the threshold. According to the temporal and spatial evolution of soil fertility and the current fertility level, it is recommended to adopt measures of "supplementing phosphorus and potassium, increasing application of organic fertilizer, and reducing chlorine" to improve soil quality.