Detailed Explanation of Key Technical Points and Application Methods of Water-Fertilizer Integration
Water-fertilizer integration technology is a new agricultural technology that integrates irrigation and fertilization. Water-fertilizer integration uses a pressurized irrigation system to deliver a fertilizer solution made by blending soluble solid fertilizers or liquid fertilizers together with irrigation water evenly and precisely to the soil around the crop roots. With fertigation technology, the water and nutrient requirements can be designed for the entire growth period according to crop growth needs, and water and nutrients can be supplied directly to the crops in fixed amounts, at fixed times, and in fixed proportions.
Pressurized irrigation includes forms such as sprinkler irrigation and micro-irrigation. The currently common form is the combination of micro-irrigation and fertilization, and most often the combination of drip irrigation or micro-sprinkler irrigation with fertilization. A micro-irrigation fertilization system consists of four parts: the water source, the head hub, the water delivery and distribution pipelines, and the emitters. Water sources include rivers, reservoirs, machine wells, ponds, and so on; the head hub includes motors, pumps, filters, fertilizer injectors, control and measuring equipment, and protective devices; the water delivery and distribution pipelines include main, sub-main, branch, and lateral pipes as well as pipeline control valves; the emitters include drip heads or sprinkler heads and drip irrigation tape.
Suitable Scope
This technology is suitable for promotion and application in areas that have a fixed water source such as a well, reservoir, or storage pond, where water quality is good and meets micro-irrigation requirements, and where micro-irrigation facilities have already been built or conditions exist for building them. It is mainly suitable for protected agriculture cultivation, orchard cultivation, and field cash crop cultivation such as cotton, as well as other crops with relatively good economic returns.
Key Technical Points
1. Selection of the micro-irrigation fertilization system
Different micro-irrigation fertilization systems are selected according to water source, terrain, planting area, and crop type. For protected cultivation, open-field melon and vegetable planting, and field cash crop cultivation, drip irrigation fertilization systems are generally selected, and for fertilization devices in protected cultivation, Venturi fertilizer injectors, pressure-differential fertilizer tanks, or fertilizer injection pumps are generally selected. For orchards, micro-sprinkler fertilization systems are generally selected, and the fertilization device is generally a fertilizer injection pump; where conditions permit, an automatic irrigation and fertilization system can be selected.
2. Formulating a micro-irrigation fertilization plan
(1) Determination of the micro-irrigation regime. The irrigation quota is determined according to the water requirement of the planted crop and the precipitation during the crop growth period. For open-field micro-irrigation fertilization, the irrigation quota should be reduced by 50% compared with flood irrigation, and for drip irrigation fertilization in protected cultivation, the irrigation quota should be reduced by 30%-40% compared with greenhouse border irrigation. After the irrigation quota is determined, the irrigation timing, frequency, and amount per irrigation are determined according to the crop water requirement pattern, precipitation conditions, and soil moisture status.
(2) Determination of the fertilization regime. There are significant differences between micro-irrigation fertilization technology and traditional fertilization technology. For a reasonable micro-irrigation fertilization regime, the total fertilizer amount, the ratio of nitrogen, phosphorus, and potassium, and the ratio of basal fertilizer to topdressing should first be determined according to the fertilizer requirement pattern of the planted crop, the fertility level of the plot, and the target yield. Fertilizer used as basal fertilizer is applied before land preparation, while topdressing is determined in frequency and amount according to the fertilizer requirement characteristics of different crops at different growth stages. Implementing micro-irrigation fertilization technology can increase fertilizer use efficiency by 40%-50%, so the fertilizer amount used in micro-irrigation fertilization is 50%-60% of that used in conventional fertilization.
Still taking protected cultivation tomato as an example, with a target yield of 10000 kg/mu, each 1000 kg of tomato produced absorbs N: 3.18 kg, P2O5: 0.74 kg, K2O: 4.83 kg, and the total nutrient requirement is N: 31.8 kg, P2O5: 7.4 kg, K2O: 48.3 kg; under protected cultivation conditions, the nitrogen fertilizer use efficiency in the current season is 57%-65%, phosphate fertilizer is 35%-42%, and potassium fertilizer is 70%-80%; to achieve the above yield, N: 53.12 kg, P2O5: 18.5 kg, and K2O: 60.38 kg should be applied per mu, totaling 132
2 kg (soil nutrient content not calculated). Then, based on the nutritional characteristics of tomato, a fertilization plan for each growth stage of tomato is formulated.
(3) Selection of fertilizers. The application of basal fertilizer in a micro-irrigation fertilization system is the same as traditional fertilization and may include various organic fertilizers and various chemical fertilizers. However, the fertilizer varieties used for micro-irrigation topdressing must be soluble fertilizers. Fertilizers such as urea, ammonium bicarbonate, ammonium chloride, ammonium sulfate, potassium sulfate, and potassium chloride that meet national standards or industry standards have relatively high purity and fewer impurities, and will not produce precipitation after dissolving in water, so they can all be used as topdressing. To supplement phosphorus, soluble fertilizers such as monopotassium phosphate are generally used as topdressing. When topdressing to supplement trace element fertilizers, they generally cannot be used at the same time as phosphorus topdressing, so as to avoid forming insoluble phosphate precipitation and clogging drip heads or sprinkler heads.
3. Supporting technologies
The implementation of water-fertilizer integration technology should be accompanied by the application of improved crop varieties, pest and disease control, and field management technologies. It can also adopt plastic film mulching technology according to the crop, forming forms such as drip irrigation under film, so as to give full play to the advantages of saving water and fertilizer and achieve the goals of increasing crop yield, improving crop quality, and increasing benefits.
Implementation Effects
1. Water saving. Water-fertilizer integration technology can reduce water infiltration and evaporation and improve water use efficiency. Under open-air conditions, compared with flood irrigation, micro-irrigation fertilization achieves a water-saving rate of about 50%. Under protected cultivation conditions, compared with border irrigation, drip irrigation fertilization saves 80-120 cubic meters of water per mu of greenhouse per season, with a water-saving rate of 30%-40%.
2. Fertilizer saving. Water-fertilizer integration technology realizes balanced fertilization and concentrated fertilization, reduces fertilizer volatilization and loss, as well as losses caused by excess nutrients, and has advantages such as simple fertilization, timely fertilizer supply, easy crop absorption, and improved fertilizer use efficiency. When crop yields are similar or the same, water-fertilizer integration saves 40%-50% of chemical fertilizer compared with traditional fertilization technology.
3. Improving the microecological environment. Protected cultivation using water-fertilizer integration technology:
First, it significantly reduces the air humidity in the greenhouse. Compared with conventional border irrigation fertilization, drip irrigation fertilization can reduce air humidity by 8.5-15 percentage points.
Second, it maintains the temperature in the greenhouse. Compared with conventional border irrigation fertilization, drip irrigation fertilization reduces the number of times ventilation is used to lower humidity and thereby lower the greenhouse temperature; the greenhouse temperature is generally 2-4°C higher, which is conducive to crop growth.
Third, it enhances microbial activity. Compared with conventional border irrigation fertilization technology, drip irrigation fertilization can increase soil temperature by 2.7°C, which is conducive to enhancing soil microbial activity and promoting crop nutrient absorption.
Fourth, it helps improve soil physical properties. Drip irrigation fertilization overcomes soil compaction caused by irrigation, reduces soil bulk density, and increases porosity.
Fifth, it reduces soil nutrient leaching loss and reduces groundwater pollution.
4. Reducing the occurrence of pests and diseases. The reduction in air humidity greatly inhibits the occurrence of crop diseases, reduces pesticide input and labor input for disease control. Micro-irrigation fertilization reduces pesticide use per mu by 15%-30% and saves 15-20 labor units.
5. Increasing yield and improving quality. Water-fertilizer integration technology can promote crop yield increases and product quality improvement; orchards generally increase yield by 15%-24%, and protected cultivation increases yield by 17%-28%. Taking protected cultivation cucumber in Yuanping City as an example, compared with conventional border irrigation fertilization, drip irrigation fertilization reduced deformed cucumbers by 21%, increased normal cucumbers by 850 kg per mu; increased cucumber yield by 280 kg per mu, and increased output value by a total of 1356 yuan per mu.
6. Improving economic benefits. The economic benefits of water-fertilizer integration technology include the benefits obtained from increased yield, improved quality, and savings in input. Orchards generally save 300-400 yuan of input per mu and gain 300-600 yuan from increased yield and income; protected cultivation generally saves 400-700 yuan of input per mu, among which water and electricity savings are 85-130 yuan, fertilizer savings are 130-250 yuan, pesticide savings are 80-100 yuan, labor savings are 150-200 yuan, and increased yield and income are 1000-2400 yuan.