The total area of land of China ranks third in the world, the land area per capita is only 0.777 hectare, one third of the world’s average per capita. The area of arable land in China in 2000 was 128,233,100 hectares. The area of arable land per capita was 0.101 hectares, less than half of the world’s average per capita. The rate of use of arable land was high, with the current rate of cultivation having reached 13.7%, 3.5% higher than the world’s average level.

In 2000, 1.566 million hectares of arable land were used for other purposes. Among this, 163,000 hectares were used for construction; 763,000 hectares returned to forestry and grassland for ecological conservation; 578,000 hectares for agricultural restructuring; 62,000 hectares destroyed by natural disasters. 291,000 hectares of land were added, 184,000 hectares through exploiting unused land, 66,000 hectares through reclaiming abandoned land and 42,000 hectares through land reconditioning. So the actual area of land used for other purposes in 2000 was 1.275 million hectares.

The sampling monitoring of harmful heavy metals in soil was undertaken on 300,000 hectares of protected arable land for agricultural production. Among this, 36,000 hectares have exceeded the standard for soil heavy metals, accounting for 12.1%.

According to incomplete statistics in 23 provinces(autonomous regions and municipalities), 891 accidents of agricultural pollution took place in 2000. 40,000 hectares of agricultural land was contaminated and a loss of 24.89 million kilograms of agricultural and husbandry products was caused, which led to a direct economic loss of 220 million yuan RMB.

The area of arable land with potassium deficiency accounts for about 56% of the total arable land area. More than 50% of the arable land was short of trace elements. There was inadequate nutrients in 70% to 80% of the arable land, but the nitrogen was excessive in 20% to 30% of the arable land. The arable land was degraded due to inadequate investment in organic fertilizers and unbalanced use of fertilizers, which led to the thinning of fertile soil, the poor cultivatability and decreased capability of water and fertility conservation. In 2000, sandstorms occurred frequently in large areas of northwest and north China. The occurrence of sandstorms was very closely related with the degraded physicochemical properties of soil, the destruction of soil granular structure and desertification.

During the ninth five-year plan period, the annual amount of agricultural chemicals was stabilized at 230,000 tons or so. Among them, the use of pesticide and miticide accounted for 62%, fungicide for 21% and herbicide for 17%. The raticide and plant growth adjusting agents made up for a very small percentage. Currently, the amount of production of agricultural chemicals in China ranks second in the world. However, the product structure is not rational and the product quality is relatively low. The pesticide accounts for 70% of the agricultural chemicals. The organic phosphorus chemicals account for 70% of the pesticide. The products with medium and high toxicity account for 70% of the organic phosphorus chemicals.

Desertification refers to the land degradation in arid, semi-arid or sub-humid area caused by climate change or human activity. According to the character and the structure of the earth surface, there are several kinds of desertification, which are caused by wind, water, salt, freezing and stone etc. Now the desertified land in China has been over 2.622 million square kilometer comprising 27.3% of the total area of China, among which the sand area is 1.689 million square kilometer. Desertification has come to be an important environmental issue and has restricted the sustainable development of the economy. Every year, the loss caused directly by desertification has reached to 54 billion yuan, and there are 10 million hectare arable land been desertification ever since the found of P. R. China.

Stalk includes corn stalk, wheat stalk, straw, oil plants stalk, bean stalk and stalk of other crops. It is the main raw material of paper making industry in China. While the scale of the paper making enterprises in China is much lower than that of the world average. Because of the old facilities and lagged technology, waste water from the paper making industry has polluted a number of water body. Few of the big paper making enterprise attain the environmental criteria. while those middle and small enterprises discharge waste water almost without any disposal, and they are the most common pollution source. Besides, the direct burning of the stalk increases year by year, leading to the low visibility along the roads.

Actually, the stalk can be used widely: Industrial material, mainly used to paper making, about 2.3%; feeding livestock, mainly for the plant-feeding animal, about 24.0%;direct burning or as biomass energy, about 31.5%. The other is left or fired out, more than 20%.

In 1998, the stalk can be obtained is 513.4 million ton. According to the specialists, the crop stalk will reach to 648 million ton in 2000, and 726 million ton in 2010. Based on the organic component and heat value of the stalk, there is a broad perspective, with the precondition of integrated utility technology. At present, the known stalk utility technology are as follows:

The first is stalk fertilizer technology, including left to field and quick compost technology. The main point of this technology is to quicken the decomposition of the organics and to increase the earth fertility in order to benefit the sustainable development of agricultural ecosystem. This is the main technology to use stalk in recent time.

Stalk feedstaff and edible fungus technology come to the second. Depending on microorganisms to transfer the nutrition in organism, increasing its economic value, then we can take it back to land. Traditional use is to feed livestock, in which how to increase the digest rate and complement the source of protein are the key point. Utilizing stalk to plant edible fungus is also a traditional technology. If new kind of fungus can be selected out and developed, or progress made on plant technology, there will be a great potential to increase its value.

The third one is technology to use stalk as energy and industry material, including stalk gasification energy industry and building, wrapper industry etc. Mostly, people use the fibre and woodness as filling material, fibreboard etc.

The organic component of different crop stalk is almost similar, but we should have our selection according to the different purpose. Stalk used as feedstaff and edible fungus should have a high content of protein, tat, and soak without nitrogen, while the content of fibrin, lignin and ash should be low; On the other hand, stalk used as building and energy material should have high fibrin, lignin and heat, while protein, fat and soak without nitrogen are unimportant.

Sandy weather refers to the weather when much dust sand are wind up by strong wind and the horizontal visibility decrease obviously. It can be divided into three types: floating dust, raising dust and dust storm.

Floating dust: sand or soil particle (often from far away or local raising sand and dust left in the atmosphere) suspend equally in the atmosphere, and make the horizontal visibility less than 10 kilometer. Raising dust: wind blow up the dust on the ground and make the air rather dirty, with the horizontal visibility between 1 and 10 kilometers. Dust storm: Strong wind blow up the dust on the ground, and make the air quite dirty, the horizontal visibility less than 1 kilometer. When the horizontal visibility is less than 500 meters, it is defined as strong dust storm.

The dust storm has many disadvantages: