Organic Fertilizer Nutrient Releasing Rate In Different Substrates And Its Effects On Tomato Growth

The experiment was carried out with three kinds of mixed substrates and two types of fertilizer (organic and inorganic). The substrates were organic mixed substrate (maize straw, legume straw v/v=1:1,ML), organic and inorganic mixed substrate (vermiculite, peat moss v/v=1:1,VPM) and inorganic mixed substrate (vermiculite, perlite v/v=1:1,VP).The types of fertilizer were chicken manure and chemical fertilizer, no-fertilization treatment was employed as control to study the nutrient releasing rate of organic fertilizer and chemical fertilizer among different treatments by room elution experiment. Meanwhile the effects of different treatments on tomato (Zhongza 105) growth, physiological characteristics, yield and fruit quality were studied by field experiment. The main results were shown as follows:1. There were obvious differences of organic fertilizer nutrient releasing rate among different substrates. The releasing rate of NH4+-N in VP was very quick and after six weeks can hardly detect NH4+-N.Compared with VP, releasing rate of NH4+-N in ML and VPM was much slower. The content of NO3--N of organic fertilizer increased in early stage and decreased in later stage in VP, VPM and ML and the releasing peak was on the sixth week, the tenth week and the twelfth week respectively. Accumulations of total nitrogen were 4.336mg, 4.732mg and 4.421mg in VP, VPM and ML during 24 weeks which account for 23.8%, 30.9% and 28.9% of added nitrogen respectively. Phosphorus releasing rate of organic fertilizer in VP was very smooth and could hardly detect phosphorus after the sixteenth week.Net phosphorus releasing trend in VPM gradually increased during the whole period. No phosphorus released in ML until the third week. Accumulations of phosphorus in VP, VPM, ML respectively accounted for 35.2%,39.3%,38.3% of added phosphorus. Releasing rate of potassium of organic fertilizer was quick and complete, the releasing curve in VP, VPM and ML was basically consistent. During sixteen weeks accumulation of potassium accounted for 84.3%, 86.1% and 88.2% of added potassium. According to the regression analysis of the experimental data, releasing amount(Y) and time(X) accorded with regression equation as follows, net releasing curve: NH4+-N and potassium accorded with Y = aXb (b <0); phosphorus, total nitrogen and NO3--N accorded with Y = aX4 +bX3+cX2+dX+e.Accumulation curve: NH4+-N and potassium accorded with Y = aLn( X)+b(b>0),NO3--N and total nitrogen accorded with Y = aLn( X)+b(b<0), phosphorus accorded with Y = aE+bX4 +cX3+dX2+eX+f. Most of the correlation coefficient of these regression equation reached significant level.2. Effects of different fertilizers on activity of enzyme in the substrates were shown as follows: Of all the treatments, Alk-phosphatase was the leading phosphatase; of the three organic fertilizer treatments, the activity of Alk-phosphatase in ML and VPM was significant higher than that in VP. No matter organic fertilizer treatment, chemical fertilizer treatment or control, the activity of cellulase, urease, proteinase and invertase in ML was significant higher than that in VPM and VP.3. As compared with respective control, the organic fertilizer treatments and chemical fertilizer treatment in VP and VPM was significant to enhance the height of tomato, fresh weight of root, stem and leaf. The differences of plant height, fruit fresh weight of tomato in the three fertilizer treatments in ML were not significant. The EC value differed a lot among different treatments, EC in organic fertilizer treatments changed more stable than that in chemical fertilizer treatments.4. The yield per plant in VPM with organic fertilizer treatment was the highest, the yield per plant was 1778.5g, which was significant higher than that in other treatments. The yield of control in VP was the lowest, the yield per plant was 148.6g. As compared with chemical fertilizer, organic fertilizer in VP and VPM significantly increased sugar/acid, content of Vc and significantly decreased nitrate content, organic fertilizer in ML significantly increased the content of soluble solid and decreased the nitrate content.