TRADITIONAL MANURING TECHNIQUES IN CHINESE AGRICULTURE AND THEIR VALUE FOR SOIL FERTILITY AND THE ECOSYSTEM

摘要

Since the 1980s, there has been a steep decline in the utilization of organic manures in Chinese agriculture. High amounts of mineral fertilizers (mainly N) are being applied, causing severe environmental problems. Two examples of traditional composts are presented: "Waterlogged compost" was the traditional manure in the Yangtze River area. Canal and river sediments (60% fresh weight), 20%-35% green matter, 0%-15% pig manure, 2-4% straw were filled into a pit and fermented anaerobically for 20-40 days. Application rates, as basal fertilizer for rice, were 25-60 t fresh matter (FM)·ha~(-1) per crop. Raw materials and different mature compost samples were analyzed for total and available macronutrients (N, P, K), organic matter and pH. Total and, in particular, available macronutrient contents were significantly increased in compost compared to soil and sediments. Hydrolizable N, available P and available K contents amounted to 35% of total N, 21% of total P and 34% of total K contents in compost, respectively. Waterlogged compost releases N, P and K relatively constantly during rice growth. "Soil manure" is a traditional farmyard manure in N- and NW-China consisting of 80%-90% soil used as bedding material and 10%-20% animal excreta. Application rates are usually between 75 and 1201 (FM)·ha~(-1)·yr~(-1). Soil manure samples were analyzed and long-term aerobic incubation experiments were carried out with soil and soil manure. Increasing additions of soil manure led to higher cumulative amounts of N mineralized during the incubation period. The multiple benefits of both composts for crop nutrition and soil fertility are highlighted. Drawbacks of traditional manuring techniques, new problems arising from the rapid economic development, and requirements under the present conditions are discussed.