Soilless culture is an efficient cultivation mode with less impact on the environment and time and labor. Although most of the nutrient solution formulations we use are mature formulations, it is easy to ignore some problems when formulating a nutrient solution, thus affecting the cultivation effect. By summarizing, the following should be noted:
1. The impact of water quality.
In the process of vegetable production nutrient solution, water is generally taken locally. Due to the large difference in water quality in different regions, water will dissolve a variety of salts, and some salts will affect the effectiveness of nutrients in the process of arranging nutrient solution.
Therefore, when applying soilless culture techniques for the first time in a certain area, before the nutrient solution is configured, the water source used for the preparation of the nutrient solution must be tested.
2. Effects of different matrices on nutrient solution configuration:
Due to the characteristics of some matrices, it will affect the pH of the nutrient solution, especially the pH value is too high, causing plant deficiency and affecting growth.
For example, the overall performance of grass charcoal is acidic or strong acidity, the rice husk is alkaline after carbonization, and the mushroom slag is alkaline.
Therefore, the choice of substrate should be taken into consideration when configuring the nutrient solution, especially for the matrix with a large influence on the pH value, and pH adjustment is needed to avoid affecting the development of the crop.
Some places choose to mix the matrix to alleviate the adverse effects of a single matrix.
3. Nitrogen concentration
Nitrogen is the most demanding nutrient element in plant growth and determines the key elements of crop yield. However, excessive nitrogen concentration is likely to cause a decline in yield and quality.
Nitrate nitrogen and ammonium nitrogen are the two main nitrogen sources directly absorbed by plants. Because plants contain ammonium nitrogen in nutrient solution, the absorption efficiency of nitrate nitrogen can be improved. In the proportioning process, if ammonium nitrogen accounts for the total When the nitrogen content is 5%, the amount of nitrogen used can be reduced by 10-20%.
Ammonium nitrogen should not exceed 30% of total nitrogen, and excessive ammonia can cause ammonia poisoning. Especially in the hot season, due to the accelerated respiration of root cells, the concentration of sugar in the roots is reduced, which can not meet the normal metabolism of ammonium, causing the accumulation of ammonia in the roots, resulting in root death.
4. Phosphorus concentration
In order to ensure sufficient phosphorus, the concentration of phosphorus in the nutrient solution is generally chosen to be twice the amount of crop absorbed.
However, more phosphorus is likely to cause the deficiency of trace elements in plants, which will affect the absorption of elements such as copper, iron, manganese and zinc, especially the high content of phosphorus can hinder the normal absorption of zinc.
5. The concentration of each element is balanced
Nitrogen, phosphorus, potassium, calcium, and magnesium are several elements of high demand for plants, which are closely related to crop growth.
Due to the influence of matrix adsorption and plant absorption rate, the content of nutrient elements in the nutrient solution is generally greater than that of crops.
However, in most cases, the deficiency syndrome exhibited by the crop is not really lacking an element but is caused by an imbalance in the concentration of various nutrient ions.
For example, excessive potassium supply will affect the balance between various ions, especially the balance between nitrogen and potassium, affecting the absorption of calcium and magnesium ions by plants.
In the soilless culture of solanaceous vegetables, the nutrient elements with relatively large demand during the whole growth period are nitrogen, potassium, and calcium, while the absorption of phosphorus and magnesium is relatively small. The ratio of potassium to calcium affects yield and quality. The most important factor is that the ratio of potassium to calcium should be around 1:1.
6. The priority configuration of mother liquor
In the nutrient solution configuration, the amount of trace elements is less, should be formulated into a mother liquid, placed in the dark place to save, with the nutrient solution in proportion.
In order to prevent crop iron deficiency, iron is generally supplied separately. Since inorganic iron is easily precipitated in a solution with high pH value, chelated iron is generally used, but it should be noted that chelated iron easily causes copper and zinc lack in crops.
Due to the influence of phosphorus and chelated iron, zinc is generally recommended to be twice the amount of nutrient solution.
The preparation of nutrient solution is the core of vegetable soilless cultivation work. Grasping the configuration process and method of nutrient solution, combined with the actual flexibility and regulation, can achieve twice the result with half the effort.