South China Degraded Land Issues

Examples of current efforts

Examples of on-going Chinese research to improve their tropical/subtropical degraded lands

One of China’s few natural “resources” that continues to grow is degraded lands. Nevertheless, some promising techniques exist in South China that have potential to improve the degraded lands, solve associated environmental problems, and improved the economic conditions of the farmers. Such techniques may help relieve the growing pressure that exists on their remaining productive lands. This author collected examples of similar techniques from South China and published them in Improving Degraded Lands: Promising Experiences from South China in 1993. These techniques provide hope that South China’s extensive tropical/sub-tropical degraded lands might once again become environmentally and economically productive. Below are three such promising research and development activities designed for degraded sites that need further demonstration, refinement, and ultimately extension to farmers .

The rubber/tea agroforestry system:

Rubber/tea agroforestry system at Xishuangbanna, Yunnan Province. (Photo by W. Parham, 1991)

The rubber/tea system is one of many agroforestry systems developed by the Chinese to help return productivity to South China’s degraded land and to provide new economic opportunities for the region’s people. The rubber/tea system involves planting bands of rubber trees between parallel bands of the tea bushes in spatial arrangements that provide the needed 30 percent shade to produce high quality tea. In the early stages of growth of the rubber and tea system when the plants are still small, the farmers plant a variety of food crops and medicinal plants between the rubber trees and tea bushes to provide for immediate income. As the rubber trees and tea bushes grow larger, the tea bushes help to moderate the microclimate near the base of the rubber trees thus protecting the near-ground parts of the rubber trees and their roots from periodic damaging cold waves. Further, the rubber/tea system helps to assure that the farmer has an income from the low-lying, flexible tea bushes even if typhoons damage the rubber trees. Numerous other benefits accrue to the farmers and the natural environment by using the rubber/tea system versus planting monocultures of either rubber or tea on degraded lands. These benefits include:

• rubber trees can be tapped for their latex one year earlier than normal and they produce greater quantities of product during their life time as do the tea bushes;
• runoff and soil erosion decrease, soil moisture, soil organic matter, and the number of beneficial soil microorganisms increases;
• enhanced size and spread of both root systems;
• carbon sequestration below and above ground increases significantly
• the income/unit area of the rubber/tea system is significantly higher than either monoculture.

(For more detail on this topic click on Related publications and then on “The rubber/tea agroforestry system of South China: a short review.“)

Stereoagriculture:

Stereoagriculture in Wuhua County, Guangdong Province. (Photo from Luo Shiming, South China Agricultural University, Guangzhou, 1991)

An important technique developed to improve degraded hilly-lands in South China is stereoagriculture, a form of Chinese ecological agriculture. Stereoagriculture generates a variety of products (e.g., food and fiber from plants and animals, firewood, and medicines) from topographically varied sites and conserves natural resources and improves damaged environments. Typically in stereoagriculture, conservation forests clad the hilltops to slow soil erosion and runoff and to increase ground-water recharge. The benefits from doing so accrue to sites at lower elevations. Hillside forests are a blend conservation and economic forestry. These forests satisfy local fuel and timber needs and needs for other forest products. Some animal grazing may occur here. Below on the flat land, lies an intercropped mixture of orchards and food crops, interspersed with fish ponds, and grazing of small animals. In this lower area, various intercropping systems provide the farm with his chosen foods. These systems take advantage of the different morphologies of the above-ground parts of various plants to develop appropriate beneficial sun and shade settings. In a similar way, the researchers determine the most beneficial spatial arrangements of the root systems of the intercropped plants to minimize competition for water and soil nutrients. As expanding industrialization and urbanization increases, the demand for flat land increases and many farmers are displaced onto hilly lands. Stereoagriculture, therefore, provides various long-lasting economic and environmental opportunities for the farmer. Stereoagriculture needs further, broad demonstrations in South China in its various forms to illustrate its benefits and to encourage its wider use by farmers.

Natural zeolite minerals used to improve degraded natural resources and farm-animal health:

Zeolites are a group of naturally occurring, fine-grained minerals with pronounced ion exchange properties. Chinese researchers are testing zeolites from South China in various agricultural settings. The researchers find that adding small amounts of zeolite to highly weathered, low-fertility soils significantly slows the leaching of fertilizer (nitrogen and potassium) into the environment and aids in releasing tightly bound soil phosphorus to the plants. Corn grown on soils amended with small amounts of the zeolite clinoptilolite had as much as a 29.5 percent increase in biomass production and improved nitrogen-use efficiency. Chickens fed a zeolite supplement required reduced feed and, ammonia pollution from chicken wastes decreased. The volume of water needed to raise turtles, instead of having to be changed every two days only had to be changed once every ten days after addition of a small amount of zeolite. Fishpond water had its BOD, COD, and NH₃ content significantly reduced , 29.3%, 50.9%, and 42.0% respectively, by the addition of small amounts of zeolite. In addition, turtle diseases decreased in zeolite-amended water while their survival rate increased.

These test data suggest that natural zeolites may find some important uses in addressing degraded land problems and in offering new economic opportunities to farmers. Zeolites can help prevent agricultural pollutants from entering the groundwater and surface waters, help make clean-water resources last longer where fish and turtles are raised in ponds, reduce chicken feed requirements, and increase the survival rate for turtles while decreasing disease.

Walterv E. Parham, Ph.D., August 1, 2009