Sustainable table, innovative agriculture
- By Duan Haiwang
0 Comment(s)
Print
E-mail China Today, May 9, 2017
 |
|
Professor Liu and his colleague collect soil samples from a kiwi orchard during their trip to New Zealand. [Photo/China Today] |
Chinese agriculture relied on organic fertilizer for 4,000 years, but since farmers switched to chemical variants a few decades ago, various problems, such as soil degradation, lower crop disease resistance, deterioration in the quality of agricultural products, and agricultural nonpoint source pollution, have arisen. What has caused this non-sustainable efficacy of chemical fertilizers? Professor Liu Cunshou of Northwest Agriculture and Forestry University shared his views on this phenomenon with China Today.
Professor Liu is an experienced agricultural scholar and practitioner. After analyzing the side effects of chemical fertilizers and carrying out groundbreaking scientific innovations, he formulated a new type of fertilizer that makes effective use of natural organic matter.
Seeking answers from virgin forest
Liu doesn't totally agree with the view that the harmful effects of chemical fertilizers are due to farmers' excessive use of them.
After carrying out research on developed countries' early use of chemical fertilizer and its later application in developing countries, Liu discovered that all concerned had encountered similar problems. He pinpointed the rule governing the process that chemical fertilizers accelerated the consumption of soil carbon, so reducing the organic matter content in soil. His research concluded that organic fertilizers could counterbalance the side effects of chemical fertilizers.
This explains why certain developed countries have recommended reverting to the use of organic fertilizers, in recent years.
"To resolve this problem, we need to discern the reason why chemical fertilizers have this side effect by distinguishing the differences between soil in its natural state and that which has been treated with chemical fertilizers," Liu said.
Liu launched his research using soil samples from virgin forests as soil there is in its natural state. He and his team studied the soluble humic acid in the soil and identified its composition and existing form. After research and experimentation, they found that natural soil is rich in various small organic molecular substances and assorted mineral elements which exist as coordination complex.
They reached three conclusions: first, plants absorb organic nutrition through their roots. Second, the healthy growth of plants requires multiple mineral elements. Third, a coordination compound can enhance the bioavailability of plants.
These findings theoretically explained the occurrence of chemical fertilizer side effects. As all chemical fertilizers are inorganic, the only minerals they provide are nitrogen, phosphorus, and potassium. Neither this range of minerals nor their existing form is sufficient to grow healthy plants. The long-term application of chemical fertilizers results in a shortfall of organic nutrition and various types of mineral nutrition. As this imbalance continues, the side effects gradually worsen.
Fertilizer industry revolution
The research Liu's team carried out revealed the decisive impact that soluble humic acid has on soil fertility and the supply of nutrition to plants.
"The principle is that where increasing the content of soluble humic acid in soil boosts soil fertility," Liu said. Humid acids are produced through biodegradation of natural organic matter, and are found in organic fertilizers. But that does not necessarily mean that applying organic fertilizers substantially boosts soil fertility and reduces the side effects of chemical fertilizers. On the one hand, the efficacy of different organic fertilizers varies greatly; on the other, organic fertilizers can only be absorbed and utilized by plants after soil microorganisms have biodegraded them into small soluble molecular substances. But the slow biodegradation process and low utilization rate in soil of organic carbon significantly affects the efficacy of organic fertilizers.
Go to Forum >>0 Comment(s)