Effect Of Water And Nitrogen Interactions On Greenhouse Tomato And Soil Environment Used Biogas Residue

A randomized complete block experiment combined with field cultivation tests and chemical analysis method was introduced to studied the effects of biogas residues and chemical fertilizer on the growth, yield and quality of tomato, the N accumulation and heavy metal pollution in greenhouse soil at different rates, and explored the optimal ratio between biogas residues and chemical fertilizer in greenhouse.In order to search the coupling effect of different irrigation levels and different fertilizer ratios on the growth, yield and quality of tomato, the N accumulation and heavy metal pollution in greenhouse soil, a randomized complete block design were adopted, based on the results of single-factor test. And further analysis to explore more appropriate mix of water and nitrogen with biogas residues in greenhouse. The results were as follows:The tomato growth was greatly improved by using biogas residues combined with chemical fertilizer. It showed that B4(40% Biogas residues and 60% chemical fertilizer combined) was the best treatment and B3(60% Biogas residues and 40% chemical fertilizer combined) was next. The results of water-nitrogen coupling showed that the couples of water-nitrogen treatment between S1(2500m3·hm-2),S2(3000 m3·hm-2),F1(60% Biogas residues and 40% chemical fertilizer combined) and F2(40% Biogas residues and 60% chemical fertilizer combined) were were better than other treatments on growth. In these treatments, S1F1 (2500m·hm-2 and 60% biogas residues and 40% chemical fertilizer combined) was the most appropriate combination, the second was S1F2 (2500 m3·hm-2 and 40% biogas residues and 60% chemical fertilizer combined).Among all the fertilizer treatments, the highest yield was B3 (60% biogas residues and 40% chemical fertilizer combined), the yield by using biogas residues and chemical fertilizer combined were higher than using biogas residues and chemical fertilizer singly. The results of water-nitrogen coupling showed that S1 was more useful to the yield than others, and S1F2 was the highest one. It showed that the coupling of 40% biogas residues and 60% chemical fertilizer combined with 2500 m3-hm-2 irrigation had the best effect on the yield of tomato. The fruit quality was affected by the fertilizer treatments too. According to the fruit quality and yield, It showed B3 was (60% biogas residues and 40% chemical fertilizer combined) the optimal treatment, and B4(40% Biogas residues and 60% chemical fertilizer combined) was next. Based on the results of water-nitrogen coupled, it suggested that combined biogas residues with chemical fertilizer was more useful to the fruit quality than the chemical fertilizer treatment only. Among them, S3F1 (3500m·hm-2 irrigation and 40% biogas residues and 60% chemical fertilizer combined) was the most suitable combination of water and nitrogen.The results showed that the crop could have sufficient N, whether it was simply using the biogas residues, or biogas residues and chemical fertilizer combined. Biogas residues and chemical fertilizer combined could improve soil fertility, and also be beneficial to the cultivation of subsequent crops. The NO3--N content of B3 was the highest one at the flowering stage and its accumulation in the soil was no significant difference with other treatment. As the NO3--N was main form absorbed by crop, the NO3--N content of B3 could absorbed completely and had great influence on the crop growth and yield. The NH4--N) content of all biogas residues treatments was low. However, the results of biogas residues combined with chemical fertilizer were lower than that only using biogas residues. It showed that biogas residues combined with chemical fertilizer were conducive to transform ammonium nitrogen into nitrate nitrogen, which could be easily absorbed by crops and not cause soil pollution. So the combination were good to improve the soil environment of greenhouse. According to the results, B3 (60% biogas residues and 40% chemical fertilizer combined) was the most suitable fertilizer combination. Furthermore, the results of water-nitrogen coupled suggested that S2 was the most suitable irrigation and S2F2 (3000m3·hm-2 irrigation and 40% biogas residues and 60% chemical fertilizer combined) was the most suitable combination of water and nitrogen. which would make soil fertile, improve soil environment of greenhouse and provide sufficient nitrogen for the crops.According to the cumulative condition of four kinds of heavy metals in the soil, it showed that B3 (60% biogas residues and 40% chemical fertilizer combined) make for to reducing the heavy metals accumulation in the soil. The results of water-nitrogen coupled showed that the accumulation of Cu, Zn and Pb under S4 irrigation were much higher than that under other irrigation condition, which indicated that high irrigation volume was likely to cause more heavy metal accumulation in soil. At low irrigation, biogas residues combined with chemical fertilizer was benefical to decrease the heavy metals accumulation in the soil.To sum up, among all the treatments, B3(60% biogas residues and 40% chemical fertilizer combined) was the most suitable fertilizer combination; the second one was B4(40% biogas residues and 60% chemical fertilizer combined). The results of water-nitrogen coupled showed that S1F2 was the most adequate combination of water and nitrogen; S3F1 was the second one, whose sum of serial number of each index was lower than S1F2; the third treatment was S1F1, slightly lower than S3F1. In a word, F1 (60% biogas residues and 40% chemical fertilizer combined) combined with water were best, especially at the irrigation amount of 2500 m3·hm-2.