Effects Of Polyhalite Formula Fertilizer On Tomato Yield,Quality And Soil Nutrients

As a quality element of vegetables and fruits,the production cost of potassium directly determines the price of high-quality agricultural products.As the production cost of high-grade potash fertilizers gradually increases,the mining of low-cost potash is also imperative.Polyhalite is a rich source of potassium salt with the formula K₂SO₄·Mg SO4·2Ca SO₄·2H₂O,which also contains a certain amount of calcium,magnesium,sulfur and other elements,the combined effect of a variety of elements has a positive effect on the improvement of crop quality and yield increase.In addition,the development and application of mixed halide will effectively improve the shortage of potassium resources in China.As a vegetable with a wide range of cultivation in land and facility production in China,tomatoes have high requirements for the grade and demand of potash fertilizer.Therefore,in order to develop potash fertilizer resources,the effects of mixed polyhalite formula fertilizer on yield,quality and soil physicochemical properties in tomato production were studied.In this study,a total of 9treatments were set up,involving one CK without potassium fertilizer treatment,two NPK formulations（N-P₂O₅-K₂O=12-12-17 and N-P₂O₅-K₂O=15-15-15）,and each NPK formula was set up with two different ratios of mixed polyhalite instead of potassium fertilizer and two fertilization ratios.In the formula N-P₂O₅-K₂O=12-12-17,there were 4 treatments,T1 was ordinary fertilization,75%T1 was T1 overall reduction of 25%;T1（P30%）means that 30%of potassium is replaced by polyhalite under the first fertilization ratio;75%T1（P30%）is T1（P30%）overall reduction of 25%.In the formula N-P₂O₅-K₂O=15-15-15,there were 4 treatments,T2was the addition of POLY4 after ordinary fertilization under the second fertilization ratio;75%T2 is a 25%reduction in T2 overall;T2（P20%）is the second fertilization ratio,20%potassium is replaced by polyhalite,and POLY4 is added;75%T2（P20%）is T2（P20%）overall reduction of 25%.The main findings are as follows:（1）When replacing part of potassium with mixed polyhalite,it has a significant effect on tomato yield.The treatment with the highest yield was 75%T1,and the N-P₂O₅-K₂O of the treatment was 12-12-17,which was 25%less fertilization than the ordinary treatment T1,and the yield could reach 123567 kg/hm².The output of T2（P20%）treatment is second,the N-P₂O₅-K₂O of the treatment is 15-15-15,of which 20%of the potassium is replaced by polyhalite and then added a mixed halide fertilizer,the yield can reach 122759 kg/hm²,an increase of 8.04%compared with the output of T2 treatment.The yield sequence of tomatoes treated with each fertilization treatment was 75%T1>T2（P20%）>75%T2>T2>T1>75%T2（P20%）>75%T1（P30%）>T1（P30%）>CK.The yield of tomatoes treated with reduced fertilization increased by13.52%compared with T1 treatment,the yield of tomatoes treated with 75%T1（P30%）increased by 8.04%,and the yield of tomatoes treated with 75%T2 treatment increased by 0.49%compared with T2 treatment.The maximum weight of 75%,T2 and T2（P20%）fruits reached166.26 g and 167.13 g,which increased by 27.17%and 27.84%respectively compared with CK treatment.All potassium fertilizer treatments were beneficial to increase tomato Vc and reduce nitrate content,and the effect of T2（P20%）treatment was the most obvious,indicating that when N-P₂O₅-K₂O was 15-15-15,20%potassium was replaced by polyhalite and then added a treatment method of heterolite to improve the quality of tomato.（2）By comparing the changes of total nutrient content in fruits and plants,it can be seen that the highest nitrogen content in fruits was 89.89 g/kg in 75%T1（P30%）,which was 7.91%higher than that of CK treatment,while the highest nitrogen content in plants was in 75%T1treatment,and its content value was 52.02 g/kg,an increase of 14.81%compared with CK treatment.The phosphorus content of T2（P20%）in fruit was 4.23 g/kg,and T2（P20%）in plants was 3.65 g/kg,indicating that the application of polyhalite fertilizer increased the absorption of phosphorus in tomatoes.The potassium content of fruit T2 treatment reached the maximum,and the potassium content of 75%T2 treatment was the largest,and the potassium content in the fruit was greater than that of the potassium of the plant.（3）The soil conductivity showed an increasing trend with the application of mixed halite.75%T2（P20%）treated the largest conductivity value of 464.75 us/cm,an increase of 52.38%compared with CK.The available potassium content values of soil under 75%T1（P30%）,T2and 75%T2 treatment reached the maximum,which increased by 48.56%,46.24%and 47.55%compared with CK treatment.Organic matter and total nitrogen reached higher content values in 75%T1（P30%）treatment,the content values were 3.10 g/kg and 1.81 g/kg,respectively,which increased by 42%and 24.91%compared to CK treatment.In summary,the application of polyhalite formula fertilizer in tomato has obvious effects,the application of polyhalite can significantly improve the yield of tomato,improve the quality of tomato and improve the level of soil fertility.In general,under the second fertilizer ratio,namely N-P₂O₅-K₂O=15-15-15,the treatment effect of T2（P20%）in which the potassium in the fertilizer was replaced by polyhalite is better,which has a wide application value in tomato planting.