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一、前言 我国长江以南的广阔地区,属湿润的热带亚热带气候区,地跨十三个省(区),土地面积约占全国总面积的1/4。当地雨量丰沛,热量充足,土地资源复杂多样,物产丰富。境内地形起伏,多山地丘陵,素有“七山一水二分田”或“八山一水一分田”之称。可见,整个地区2/3以上的总面积为山地丘陵所据。土壤大多有不同程度的富铝风化,属多种类型的红壤、黄壤。河谷平原多种水稻,产量约为全国水稻总产量的90％。这里不仅盛产热带亚热带水果(如柑桔、龙眼、荔枝与香蕉等),而且还盛产油茶、油桐、漆与乌桕等木本油料和经济林木。这个山区又是我国竹木主要产地,珍贵水产丰富。因此本区历来是我国农林牧副渔的重要生产基地,有“鱼米之乡”的称誉。 但是过去对广大丘陵山区的自然资源,未能合理开发利用,加之长期以来片面强调粮食生产,掠夺式的经营,重采轻造、毁林开荒、陡坡垦殖、烧山取肥、铲草皮等,违背了自然规律和经济规律,以致富饶的自然资源遭到破坏,有利的生态失去平衡,水土流失日趋严重,水旱灾害频繁出现,水冲沙压良田。这就导致粮食生产基地的土壤贫瘠化,造成低肥低产状态。
I. INTRODUCTION The vast area south of the Yangtze River in our country is a humid tropical subtropical climate zone spanning thirteen provinces (autonomous regions) and covering about 1/4 of the country’s total land area. Local abundant rainfall, adequate heat, complex and diverse land resources, rich products. The territory of undulating terrain, mountainous hills, known as “seven mountains and one water two fields” or “eight mountains and one water field” said. It can be seen that the total area above 2/3 of the whole area is based on the mountain hills. Most of the soil has varying degrees of aluminum-rich weathering, is a variety of types of red soil, yellow soil. A variety of paddy plain valley, the output is about 90% of the total output of rice. Here is not only rich in tropical and subtropical fruits (such as citrus, longan, lychee and banana, etc.), but also rich in Camellia oleifera, tung oil, paint and tallow trees and other woody oil and economic forest. This mountainous area is also the main origin of bamboo in our country, with rich aquatic products. Therefore, this area has always been an important production base of our country’s agriculture, forestry, animal husbandry and fishery, and has the reputation of “hometown of fish and rice.” However, in the past, natural resources in the vast hilly and mountainous areas were not rationally exploited and utilized. In addition, the long-standing emphasis on grain production, predatory management, light harvesting, deforestation, reclamation of steep slopes, harvesting of mountain and grass, Violated the laws of nature and economy, so that the rich natural resources were destroyed, the favorable ecology was out of balance, the soil and water loss became increasingly serious, floods and droughts were frequent, This has led to the impoverishment of soils at food production sites, resulting in a state of low fertility and low yields.