Environmental Degradation and Dryland Agro-Technologies in Northwest China by Elijah K. Biamah Michael K. Biamah

Author:Elijah K. Biamah, Michael K. Biamah [Elijah K. Biamah, Michael K. Biamah]
Language: eng
Format: epub
ISBN: 9781911412212
Barnesnoble:
Publisher: Dolman Scott Publishing
Published: 2017-07-14T00:00:00+00:00

Figure 3.2. Soil and Water Management System for Sloping and Flat Lands in Northwest China (Biamah, 1994; 1996).

The most effective and sustainable way of utilizing both sloping and flat farmlands in these areas is by ensuring that adequate soil and moisture conserving techniques (both engineering and biological measures) are incorporated into the farming systems(see Figure 3.3). Then the prevailing problems of soil erosion and low soil moisture would be overcome (Biamah, 1994;1996).

3.6 Drought and Soil Water Use

According to available long term weather data, recurrence of drought of varying magnitudes is a common phenomenon within the dryland farming areas of Northwest China. For instance in Cheng Cheng Experimental Station, Shaanxi Province, 23 years of weather data(1963 to 1985), have showed that out of the 61 droughts experienced, 17 were very severe, 24 were less severe and 20 were mild. Besides these droughts, there have been some significant decrease in mean annual rainfall from 649.6mm in 1981 to 421.4mm in 1994. In Mizhi Experimental Station, Shaanxi Province, available rainfall data of ten years (1982 to 1991 ),show a mean annual rainfall of 431 .9mm and a recurrence of drought once every one to two years. The mean annual rainfall received in the ten year period ranged from 296mm to 529.7mm. These trends in rainfall are indicative of the persistence of drought in these areas (Biamah, 1994).

Given that 60% to 70% of the expected annual rainfall falls between the months of July to September when cultivated land is fallow, it is imperative that as much rainwater be conserved during this period to sustain crop growth in winter and spring. Thus soil and water management techniques used during this period should:-Increase soil water storage in the soil by enhancing infiltration and minimizing surface runoff water; and decrease evaporation from bare soil. The traditional technique that is commonly used in the area involves five tillage operations of shallow ploughing, deep ploughing, mo-harrowing, shallow ploughing and ridging (includes compaction of soil) before planting. Other new techniques for summer and autumn water management introduced involve medium tillage to loosen the soil and minimize capillary rise; use of straw and plastic film mulching, subsoiling, rotary tillage, deep ploughing and mo-harrowing (Biamah,1994;1996).

In order to optimize on available soil water use, a series of moisture saving techniques that were recommended after some extensive research included:- Early planting to control losses of soil water; compaction of soil to improve the hydraulic contact of soil and seed and hence the availability of moisture for seedling emergence; use of chemicals as foliar sprays to minimize evapotranspiration by lessening the water uptake by plants; and use of drought resistant/ high yielding crops to improve water use efficiency. Also several crop rotational programs have been experimented on (e.g. in Cheng Cheng, Shaanxi; and Dingxi, Gansu). In Cheng Cheng, a wheat-wheat-wheat-beans rotation in three years was found to have a high water use efficiency(Biamah,1994;1996).

For orchards and vegetable gardens, supplemental runoff irrigation from runoff saving techniques like underground water wells (Shui Jiao) have been encouraged to optimize yields.

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