河北坝缘简育干润均腐土耕种过程中的退化研究

STUDY ON UAP-USTIC ISOHUMISOL DEGRADATION UNDER FARMING IN HEBEI,CHINA

研究区位于中国干草原干润均腐土的东南缘、农牧交错带、荒漠化严重发展区。农业的大发展仅数十年历史，广种薄收、粗放经营形式下，土壤资源过度利用导致了耕种简育干润均腐土成为区内严重退化的类型，并集中地表现在养分、质地和保水性三方面。在肥力退化过程中，养分剖面构型向干旱土类演替；表土粗化，平耕地粒度向风沙沉积特征发展；随耕种年限的增加，耕地在养分、质地以及容重退化的同时保水保肥能力降低。缓解与治理简育干润均腐土退化需推广保护性耕作措施，改造传统农业，增加投入。

The studied area is located at the southeastern edge of the steppe Uap-Ustic Isohtumisols, being a transitional zone between farming and animal husbandry, with seriously desertified lands. Although farming was developed there on a large scale in the past decades, extensive cultivation and overuse of soil resources has made UaP-Ustic Isohumisols become seriously degraded. The soil degradation was mainly reflected in the changes of soil nutrients, soil texture and water retention. The nutrient distribution with soil depth changed towards that of Aridisol. The contents of gravel and sand increased obviously in the plough horizon. Mechanical composition of that flat farmland developed towards that of aeolian sand sediment. With the increase of farming years the degradation of nutrients, texture and bulk density weakened the soil abilities of water and fertility retention. The mitigation and control of Uap-Ustic Isohumisol degradation need to popularize protective farming techniques, remodel traditional agriculture and increase farming investment.