The multi-utilization rate of the straw of the three staple grains drags the back leg.

China is a large agricultural production country with a long history of planting industry. With the continuous expansion of the scale of agricultural production, a large number of concentrated straw has been produced, and the annual output of crop straw is 6.5 × 108 tons.

According to statistics, the proportion of straw returning to the field and fodder returning to the field accounts for about 32% of the total output, the amount of straw used as industrial raw materials is about 20% of the total, and the amount of straw resources wasted or burned is more than 45%. Straw incomplete combustion will produce a large number of nitrogen oxides, sulfur dioxide, hydrocarbons and soot, which seriously pollute the environment.

In recent years, the Ministry of Agriculture has carried out the project of returning straw to the field, which is an important way to continuously improve and improve soil fertility. Although its role is generally recognized, but in the implementation process is restricted by temperature, climate, machinery and equipment, cost and other factors, the promotion progress is still restricted. How to solve this problem scientifically and reasonably has become an important topic in academic research.

Turn "waste" into treasure

It is estimated that if the amount of straw incineration is reduced by 200 million tons every year, the emission of carbon dioxide will be reduced by about 214 million tons, and the losses caused by fires and traffic accidents caused by straw burning will be reduced by more than 50%, thus reducing the economic loss by about 100 billion yuan.

In addition, suppose that we realize the industrialization of straw in the producing area, such as the production of biodiesel, straw organic fertilizer, straw biological feed, straw board instead of wood, etc., which can not only make effective use of the rich human resources in rural areas of our country, but also bring rich income to growers in the planting area, increasing the income by 300 yuan to 400 yuan per mu.

The data show that the available amount of straw in our country is about 680 million tons every year, and the direct benefit can reach 340 million yuan every year, which is a large income for the construction of new countryside.

In Shuangcheng, Heilongjiang Province, an enterprise uses straw to produce environmentally friendly furniture, environmentally friendly packaging, and environmentally friendly building materials, which can not only solve the problem of resource utilization of straw, but also increase enterprise income by way of export. so that straw resources into economic advantage; many breeding enterprises in Liaoning and Jilin use biotechnology to make straw into cattle and sheep feed, the test results show that this kind of feed can improve the quality of meat.

With the guidance of national policy, straw biogas and straw power generation technology have been implemented in most areas of our country, which has explored a new way for straw utilization. In recent years, more than a dozen straw biomass power plants have been built in China.

However, the technological details of straw utilization are not perfect, straw deep processing cost is higher than similar products, straw utilization rate is low, and there is a lack of strong market operation.

outside the box

Throughout some technologically developed countries in Europe and America, their utilization of straw resources is more scientific and effective, which significantly improves the utilization and value of straw, which is worth using for reference.

For example, in Canada, when corn, rice, wheat and other crops mature, farmers will use combine harvesters to crush the straw to 3cm ~ 5cm while harvesting the crops, and the crushed straw will be returned directly to the field to increase the content of organic matter in the soil. In the United States, 26 million tons of straw from corn, rice and other crops are used to make biological feed every year; about 9.2 million tons of straw are pressed into blocks to fill the walls of houses; and 14 million tons of straw are used as a new biomass fuel. that is, ethanol is extracted from straw for reuse, so that the comprehensive utilization technology of straw resources can be further developed.

The comprehensive utilization of straw resources has also been supported by the local government in terms of policies and funds. In Denmark, for example, growers pack straw and sell it to power plants, which burn straw to generate electricity and provide cheap electricity to residents. In other words, farmers use straw to replace part of the electricity bill, and the straw ash produced by straw power plants is returned to the field directly by farmers, providing nutrients for farmland and realizing the organic cycle of industry and agriculture.

Direction of development

The investigation shows that the straw in our country is mainly corn, rice and wheat. The annual available amount of straw is 680 million tons. In 2010, the utilization amount was about 500 million tons, and the comprehensive utilization rate of straw reached 70.6%, which was mainly concentrated in feed processing, fuel use, edible fungus base materials and so on.

Although the comprehensive utilization of straw has achieved certain results, such a large resource should have a better development prospect.

Fertilizer: the main way of utilization is to return the field directly after crushing or to add organic material ripening agent to return to the field. This method is feasible and effective in the south of China. However, in northern China, due to the low temperature in the fallow stage, straw can not be decomposed quickly, and microorganisms can not play a role, so it is not feasible in most areas of northern China. Second, straw reactor technology is mostly used in protected areas and cash crops, and the application effect is good, but it has not been popularized because of cumbersome operation, large amount of labor and so on. In recent years, Shenyang Institute of Applied Ecology, Chinese Academy of Sciences has made straw and beneficial microorganisms into straw boards, which can be directly laid in the working soil to reduce the depth of digging, and beneficial microorganisms can enter the soil and activate nutrient elements in the soil. Third, straw can be used as organic fertilizer together with livestock and poultry breeding waste. Fourth, after straw crushing, after microbial decomposition and activation, cellulose and other nutrients are transformed to replace peat and peat resources, and seedling substrates, cultivation substrates and flower nutrient soils are made, which can reduce the development of peat and peat resources and reduce damage to wetlands and the environment.

Feed: in 2010, the number of livestock and poultry farming in China's large-scale breeding enterprises was 110 million cattle, 460 million pigs and 5.35 billion poultry respectively. The proportion of straw returning to the field and feed returning to the field accounts for about 32% of the total output, which mainly includes straw silage technology, ammoniation technology and straw kneading silk puffing technology.

Energization: data show that the use of straw as fuel in China is about 122 million tons, accounting for about 17.8% of the total. At present, the main promotion in China is straw fuel block, biological carbonization, biogas and combustion power generation. Among them, straw fuel block technology is not limited by scale, and there is no requirement for straw sources, so it has a good development prospect in solving straw pollution in rural areas; straw biogas can produce methane and other gases to provide fuel for urban and rural areas, but also can convert gas into electricity, this technology has been implemented in some parts of our country. Straw combustion direct power generation is theoretically feasible, some large enterprises in China have been implemented many years ago, but due to lax quality control of raw materials, resulting in poor efficiency, most enterprises are in a state of maintenance.

Materialization: with the continuous improvement of the process of urbanization in China, people's demand for wood is increasing day by day, resulting in massive felling of trees, which is in short supply. However, crop straw contains a lot of cellulose and lignin, these resources are not used reasonably. If the straw is made into plates and composite materials, the deforestation of forests can be reduced. In addition, adding an appropriate amount of straw to the production of edible fungi can also meet the growth of edible fungi and reduce the demand for sawdust.