In view of the large differences in the amount of organic fertilizer applied in different fields in kale production, the phenomenon of blindly applying nitrogen fertilizer is serious, the amount of potassium fertilizer is insufficient, the phenomenon of "heavy macroelements and light medium elements" in fertilization is common, the application period and method are unreasonable, and excessive Irrigation causes widespread waste of water and fertilizer, and the following principles of fertilization for kale are proposed:
(1) Reasonable application of organic fertilizer to kale, application of organic fertilizer and chemical fertilizer, application of nitrogen, phosphorus and potassium fertilizers should follow the principles of nitrogen control, phosphorus stabilization, and potassium increase.
(2) The fertilizer distribution of kale fertilization is mainly based on the combination of base and topdressing; topdressing is mainly nitrogen fertilizer, and potassium fertilizer is applied reasonably.
(3) Pay attention to properly spraying calcium, boron and other medium and trace elements in kale from the rosette stage to the late stage of nodding to prevent the occurrence of diseases such as "dry heartburn".
(4) When the acidification of kale soil is serious, an appropriate amount of acid soil conditioners such as lime should be applied.
(5) The combination of kale planting and high-yield cultivation technology, especially water-saving irrigation technology, can give full play to the coupling effect of water and fertilizer and improve the utilization rate of fertilizer.
(1) Base fertilizer is applied once, and high-quality farmyard manure is applied at 30 cubic meters per hectare.
(2) The yield level of kale is more than 97,500 kg/ha: nitrogen fertilizer (N) 270-300 kg/ha, phosphate fertilizer (P2O5) 120-150 kg/ha, potash fertilizer (K2O) 210-240 kg/ha.
(3) The yield level of kale is 82500~97500 kg/ha: nitrogen fertilizer (N) 225~270 kg/ha, phosphate fertilizer (P2O5) 90~120 kg/ha, potash fertilizer (K2O) 180~210 kg/ha.
(4) The yield level of kale is 67500~82500 kg/ha: nitrogen fertilizer (N) 195~225 kg/ha, phosphate fertilizer (P2O5) 60~90 kg/ha, potash fertilizer (K2O) 120~150 kg/ha.
For plots with severe "dry heartburn" in kale in previous years, pay attention to nitrogen control and calcium supplementation. You can spray 0.3%~0.5% calcium chloride (CaCl2) solution on the foliage of kale from the rosette stage to the late stage of nodding 2~3 times. When the soil pH of the kale garden is less than 5, 1500-2250 kg of quicklime should be applied per hectare; when the soil pH is less than 4.5, 2250-3000 kg of quicklime should be applied per hectare. For boron-deficient plots, 7.5-15 kg/ha of borax can be applied, or 0.2-0.3% borax solution can be sprayed 2-3 times on the foliar surface. At the same time, 2 to 3 times of 0.5% potassium dihydrogen phosphate can be combined with spraying to improve the clean rate and commodity rate of kale.