Three Values Of Biochar in Agricultural Application

Search on HowNet with "biochar" as the key word (data interception 2004-2021), we can see that the research on biochar is increasing day by day. HowNet only published 10 related papers in 2004, 1871 in 2021, and it is still increasing in 2022.
In Baidu search engine, the word "biochar" has been used as the keyword search, and the popularity of the word has also been growing in the past decade. This fully shows that biochar has become the focus of global scientific research and media attention.
Figure 1 Statistics of the number of papers on biochar on www.cninfo.com.cn
Biochar is conducive to reducing straw burning
With the continuous development of economy and the rapid improvement of people's living standards, people pay more attention to the quality of agricultural products and the environmental requirements in the production process.
Although China's grain output has achieved "18 consecutive successes", it has also exposed a series of problems such as land overdraft, increased soil pollution, straw burning, and unreasonable application of chemical fertilizers [1].
Most intuitively, the materials of biomass carbon can be animal manure, crop straw, bamboo, rice husk, etc., which can effectively reduce straw burning, animal manure pollution and other phenomena.
In fact, straw returning is not suitable for all areas. In areas with insufficient accumulated temperature, heavy soil viscosity, heavy rainfall and poor drainage, the yield of fields and fields tends to decrease; The effect of straw returning on water conservation and yield increase is significant in areas with good accumulated temperature and frequent drought and in years.
In areas that are not suitable for returning straw to the field, how do farmers deal with the straw piled up in the field?
This is also one of the main reasons why straw burning has not been banned for many times. But now it is possible to reduce straw burning, effectively improve the quality of cultivated land and improve soil fertility by heat treating straw in the field into biochar and returning it to the field.
Biochar is conducive to reducing the application of chemical fertilizer
With the increase of labor costs, the planting of crops has also moved from the original "intensive cultivation" to "extensive" management. Many farmers are trying to reduce the frequency of fertilization in order to save labor costs. Although theoretically, the main fertilizer demand time of crops is not in the seedling stage, there are still many farmers who apply fertilizer to the farmland in a "one shot" way with sowing.
However, due to the poor water storage and fertilizer retention capacity of most soils, soil fertilizer nutrients are leached, more fertilizers are needed, and unused fertilizers cause environmental pollution.
Although the mineral nutrient content of biochar is low, its direct nutrient effect is limited.
On most soils, the promotion of biochar on crop growth and yield is rarely related to its direct nutrients, but biochar can effectively improve the soil's ability to retain water and fertilizer, delay the release of water-soluble fertilizers in the soil, extend the effective period of nutrients, and even synchronize with crop nutrient absorption, which can greatly reduce nutrient leaching, promote crop nutrient absorption, and improve fertilizer utilization.
Biochar helps reduce carbon emissions in production
The application of chemical fertilizer is an important measure to ensure the stable and high yield of grain in China. However, excessive application of chemical fertilizer and low utilization rate lead to environmental pollution, thus affecting the green, healthy and sustainable development of agriculture.
Research shows that the carbon emissions caused by excessive fertilizer application in China account for more than 60% of agricultural carbon emissions.
Biochar can inhibit the decomposition and mineralization of soil organic matter and reduce the emission of soil CO2 after being applied to soil. The application of biochar can also reduce N2O emissions from rice fields. Because the addition of biochar increases the pH value of soil, it is conducive to the activity of N2O reductase and the reduction of N2O.
expectation
Many studies have pointed out that the application of biochar can increase the quality of crops, improve their nutrient content, and also slow down the impact of salt stress on crops, so as to develop saline alkali land and increase the reserve of arable land in China.
It can be said that biochar has many benefits in agriculture, but it must take into account the enrichment of heavy metals by organisms. At present, straw pyrolysis of most crops will significantly reduce their potential ecological risks, but the potential ecological risks of rice biomass may increase due to the increase of Er (potential ecological risk factor) value of heavy metal Cd, Therefore, for the application of biochar, it is necessary to consider the biomass with high ecotoxicity of heavy metals such as Cd, pay attention to its environmental risks, and make better use of biochar.