A. Nutrient restitution doctrine
In 1840, the outstanding great German chemist Li Bich proposed that as human beings continue to cultivate crops. The nutrients in the soil will become less and less due to the absorption and removal of crops. Which will inevitably lead to a decrease in ground power.
The doctrine of nutrient restitution is the first fundamental principle of fertilization and is the starting point. And end point of precise fertilization measurement.
B. The minimum nutrient law
1.Meaning of minimum nutrient law
Minimum nutrient law is also clearly proposed by the German Li Bich in the book “Chemistry in Agriculture and Physiology” written in 1843. Its central meaning is: plants need to absorb various nutrients in order to grow and develop. But what determines plant yield is the smallest relative content of nutrient factors in the soil. And the yield changes relatively with the increase or decrease of this factor to a certain extent.If this factor is not met, ven if other nutrient factors are increased, plant yield is not likely to increase.
2.Application of the minimum nutrient law
The fertilization practice in our city fully proves. That the law of minimum nutrients is an important guideline for the rational application of fertilizers and the development of agricultural production. And that nitrogen was the minimum nutrient factor limiting yield improvement in the 1950s. Therefore, the effect of applying nitrogen fertilizer to increase yield was very significant. While the effect of applying phosphorus and potassium fertilizer was obviously very low. Since then, the effect of nitrogen fertilization has been gradually reduced as the application of nitrogen increases year by year. Relatively speaking. At this time, due to the relative lack of soil phosphorus supply level. Phosphorus has become the minimum nutrient factor limiting the yield.
As a result, crop yields increased significantly with the addition of phosphorus fertilizer to the nitrogen fertilizer. In the 1980s, with the improvement of the replanting index, the crop yield level further increased. After the nitrogen and phosphorus nutrients were satisfied. Soil potassium became the new minimum nutrient factor, which restricted the further increase of crop yield. Our city at the same time in the 80s, zinc deficiency caused by rice “shrinkage disease”. In the province’s earliest clear production verification. Rice seedlings in general application of zinc fertilizer became the general consensus of the population.
This shows that the minimum nutrient in the soil is not fixed. It will change according to the soil, planting system, fertilization techniques, crop yield requirements and quality requirements. At the same time, the minimum nutrient can be a large amount of elements or a trace element. Correct treatment of the minimum nutrient law, try to balance the supply of nutrients, crops can fully utilize nutrients, so as to achieve increased yields, fertilizer savings and improve the effectiveness of fertilizer effect。
C. The optimum factor law
In 1895, the German scholar Liebherr put forward the law of optimum factor, which means: many conditions affect the growth and development of plants, the living conditions of a wide range of changes, plants have a limited ability to adapt. We can only influence the factors in the middle position, the most suitable for plant growth, the yield can reach the highest. And the optimum amount of any factor has variability, within a certain range, it will change with other factors.
D Michelich doctrine
At the beginning of this century, the great German agricultural chemist Michelich oats as the material for the phosphorus fertilizer sand cultivation experiments in-depth and precise discussion of the quantitative relationship between the amount of fertilizer and yield, to obtain a precise differential equation, which connotes: the effect of a nutrient to the more deficient in the soil the better the effect of the nutrient, if gradually increase the amount of the nutrient application, the effect of yield will gradually decrease.
E. Factor synthesis law
As early as 1905 by the British Blackman integrated action law, in 1984, Willens did a further improvement. The central content of the law of integrated factor action is: crop yield is the result of the integrated action of water, nutrients, light, temperature, air, varieties, tillage conditions, cultivation measures and other factors. Among them, there must be a dominant limiting factor, and yield is to a certain extent subject to the constraints of this limiting factor.
Therefore, in order to give full play to the yield-enhancing effect of fertilizers and improve the economic benefits of fertilizers, we should, on the one hand, closely coordinate fertilization measures with other agricultural technology measures and, on the other hand, strengthen the application of various fertilizers in conjunction with each other and try our best to promote a balanced supply of nutrients. The law of integrated action of factors has the most realistic guiding meaning in facility agriculture. The integrated action of factors has the effect of significantly improving the utilization rate of fertilizers and enhancing fertilizer efficiency without increasing the amount of fertilizers applied.