Can Organic Fertilizer Replace Chemical Fertilizer? A 30-Year Continuous Experiment Provides the Answer
Can crop production do without chemical fertilizers? Can organic fertilizer really replace chemical fertilizer? And how should the replacement be done? How can scientific fertilization ratios achieve both high yield and quality while minimizing environmental pressure? These hot topics that the industry has long been exploring recently found scientific conclusions and answers at the on-site meeting on long-term experiments for reducing fertilizer application and improving efficiency and demonstrations of new-type fertilizers held in Dezhou, Shandong.
No fertilizer is no good, and too much fertilizer is no good either
Recently, reporters visited the Yucheng Experimental Base of the Chinese Academy of Agricultural Sciences. This experimental base, established in the 1960s, has conducted long-term positioned experiments on different fertilization systems combining organic fertilizer and chemical fertilizer for more than 30 years. Because of its complete design and long duration, it has been praised by foreign experts as “unique in the world,” and the many years of persistent experimentation also make the results more convincing.
The reporter saw that the experimental base was divided into multiple plots of the same area, respectively treated with no fertilizer, conventional-rate chemical fertilizer, conventional-rate organic fertilizer, combined organic and inorganic application, high-rate chemical fertilizer, and high-rate organic fertilizer. Wheat in these plots under different fertilization treatments showed clearly different conditions.
In the no-fertilizer control plot, the wheat grew sparsely and short, forming a strong contrast with the surrounding plots. “This plot, which has completely gone without fertilizer for many consecutive years, yields at most two or three hundred jin per mu, while applying fertilizer can achieve a yield of more than 600 kg per mu. The difference is huge. If no fertilizer is applied in a given year, the yield will immediately drop by half.” introduced Zhao Bingqiang, a researcher at the Institute of Agricultural Resources and Regional Planning of the Chinese Academy of Agricultural Sciences, who is in charge of the project.
No fertilizer is no good, and too much fertilizer is no good either. Many years of experiments at the base show that when the amount of chemical fertilizer applied was doubled, the yield was not higher, but the environmental risk increased greatly. Zhao Bingqiang pointed out that long-term excessive application of chemical fertilizer or organic fertilizer, although it can ensure high crop yield, quality and soil fertility, causes serious fertilizer loss and prominent environmental problems: the soil nitrate content under doubled chemical fertilizer application reached 800 mg per kg, which is 16 times the threshold value; the soil nitrate content under doubled organic fertilizer application exceeded that of conventional chemical fertilizer, and in particular, the long-term large-scale application of organic fertilizer creates a relatively high environmental risk of excessive phosphorus accumulation in the soil.
Combining chemical fertilizer and organic fertilizer draws on each other's strengths for better results
So, comparing chemical fertilizer and organic fertilizer, is it better to use organic fertilizer? Long-term experiments have given a clear answer to this —— in terms of environmental risk, under the condition of equal nitrogen input, the environmental problems of organic fertilizer are significantly smaller than those of chemical fertilizer. For example, ammonia volatilization from farmland treated with organic fertilizer was reduced by 94% compared with chemical fertilizer, and the nitrate accumulation in the soil body was only 1/6 of that under chemical fertilizer treatment.
Organic fertilizer can build soil fertility and improve soil structure, but it also has its disadvantages. Zhao Bingqiang introduced that organic fertilizer has a weak nitrogen-supplying capacity. With 100% organic fertilizer application, crops are not likely to obtain high yield and quality in the short term. For example, the nitrogen supply of cattle manure during the winter wheat season is only equivalent to 1/3 of that of chemical fertilizer, so under the condition of equal nitrogen input, the yield-increasing effect of organic fertilizer in the early stage is lower than that of chemical fertilizer. After about 12 to 15 years, the yield-increasing effect of organic fertilizer on winter wheat can reach the level of an equal amount of chemical fertilizer, and the yield-increasing effect of organic fertilizer on summer maize can only become comparable to chemical fertilizer after 5 years. “Too much organic fertilizer also causes problems. Although the environmental risk of nitrogen is small, the environmental risk of phosphorus is large. The important conclusion we reached is that for winter wheat-summer maize farmland in the Huang-Huai-Hai region, applying half chemical fertilizer plus half organic fertilizer in combination draws on each other's strengths, ensuring high yield and quality, building soil fertility, and greatly reducing environmental risks such as ammonia volatilization from farmland and nitrate accumulation in the soil body.”
“The data from the 30-year positioned experiment clearly answer a series of major scientific questions such as reducing application and improving efficiency.” Chen Mengshan, secretary of the Party Leadership Group of the Chinese Academy of Agricultural Sciences, said that scientific fertilization has three purposes: first, to achieve high yield and high efficiency; second, to ensure sustainable use of soil; and third, to achieve green development and control environmental pollution. A very important measure is to combine China's traditional farming civilization with modern scientific fertilization, and to combine chemical fertilizer with organic fertilizer. Developed countries such as those in Europe and America have achieved continuous increases in crop yields while achieving zero growth and negative growth in chemical fertilizer use. An important pathway has been strengthening the utilization of organic fertilizer resources. China has abundant organic fertilizer resources. The scientific research results of the Dezhou Experimental Station give us important inspiration: the scientific combined application of chemical fertilizer and organic fertilizer has explored a path for achieving high yield and quality, building soil fertility, and protecting the environment at the same time.
To reduce fertilizer, first improve efficiency; new-type fertilizers show their prowess
To achieve reduced chemical fertilizer application and improved efficiency, and green increases in agricultural production, in addition to replacing chemical fertilizer with organic fertilizer, improving fertilizer use efficiency through new-type fertilizers is also an important pathway.
In a wheat field for improved seed breeding at the Dedi Planting Professional Cooperative in the Dezhou Economic Development Zone, the reporter saw that large areas of wheat stood tall and robust, growing impressively. This is also the value-added fertilizer green yield-increase demonstration field of Dezhou Denong Seed Co., Ltd. “This year's yield will definitely be good!” introduced Zhang Wenguo, the cooperative's technical director. Last year, wheat yield reached 700 kg per mu, and maize became the grain king of Dezhou with a yield of more than 960 kg. Such high yields were achieved not only by relying on its own improved seed advantages, but also thanks to the application of new value-added fertilizer products.
“Using new-type fertilizers developed by the new fertilizer innovation team of the Chinese Academy of Agricultural Sciences, such as zinc humic acid compound fertilizer, zinc humic acid ammonium phosphate, and zinc humic acid urea, the wheat has a well-developed root system, strong growth potential, and fewer diseases. Fertilizer costs decreased, and yield still increased by 10%.” Zhang Wenguo said.
New high-yield varieties, new value-added fertilizer products, integrated water and fertilizer management, new sowing technologies, full-process prevention and control of diseases, insects, and weeds…… integrating these green yield-increase technologies, the Dezhou Experimental Station of the Chinese Academy of Agricultural Sciences and the Dezhou Municipal Agriculture Bureau began cooperation in 2008 to carry out large-scale green high-yield demonstrations of winter wheat-summer maize across the entire system in Dezhou. Fertilizer use efficiency increased by 8 percentage points, application was reduced by 10%, and yield increased by 15%; winter wheat yield exceeded 700 kg per mu, summer maize yield reached more than 800 kg per mu, and annual grain yield per mu exceeded 1500 kg. In recent years, most of Dezhou's wheat and maize grain kings have come from the high-yield demonstration fields of the green yield-increase model carried out through cooperation between the two sides.
Zhao Bingqiang told reporters that new-type fertilizers represented by black urea have good effects and high cost performance. For a cost increase of only a few dozen yuan per ton, the benefit can increase by nearly 2000 yuan. The effect of 40 kg of black urea is equivalent to 50 kg of ordinary urea, and with the same amount, yield increases by 10%, making it easy for farmers to accept. This is also the reason why value-added fertilizers are so popular today.
“To reduce chemical fertilizer, efficiency must first be improved.” Chen Mengshan said that our new fertilizer innovation team, together with the Dezhou Experimental Station, spent ten years sharpening a single sword, established a new concept of carrier-based efficiency-enhancing fertilizer manufacturing, and developing new high-efficiency fertilizers is a convenient pathway to resolving environmental contradictions and achieving green yield increases.
It is understood that in recent years the New Fertilizer Engineering Technology Center of the Dezhou Experimental Station has developed more than 20 new fertilizer products, was authorized 29 invention patents, and has achieved transformation and industrialization of results in more than 30 large fertilizer enterprises. At present, value-added fertilizer production capacity has exceeded 10 million tons, output has exceeded 5 million tons, promotion has covered 150 million mu, grain output has increased by 4.5 billion kg, and benefits have increased by 6.3 billion yuan.