Effects of composts on tomato growth and soil fertility
This study worked with tomato plants, one soil and one peat moss, and three different composts, addressing the effects of composts and their combinations with soil and peat moss on tomato growth and soil fertility, and reduction of phytotoxicity of immature compost caused by high NH4 content.
Different composts affected tomato growth differently due to nutrient differences existing among the composts. The higher the nutrients content the better the growth. Using peat moss greatly promoted tomato growth through fertilization and increased nutrient accumulations in plant leaves and soil nutrient residual availability, but this effect was limited to compost containing high content of nutrients. Under normal fertilization practice, each of the various plant growth indices showed highly correlated relationship with total plant dry weight, thus some of the growth indices, such as numbers of plant leaf and flower, could be used to predict tomato production without undertaking destructive harvest. Also each of the major plant nutrients accumulated in plant leaves showed a highly correlated relationship with total plant dry weight.
The maturity of compost was an important factor in assessing the effects of composts on tomato growth and soil fertility. Plants growing in the mature compost medium benefitted from fertilization with nitrate, using NO 3 nutrient greatly increased plant growth and nutrient accumulations in plant leaves and also increased soil K residual availability. Plants growing in the immature compost medium benefit from fertilization with K, using K nutrient tremendously increased plant growth and nutrient accumulations in plant leaves. Immature compost was improved in their capacities to increase plant growth if additional K fertilization was provided. Fertilization with adequate dosage of K was a very effective method to reduce phytotoxicity caused by high content of NH4 in immature compost. The proper dosage set by this research was 0.6 g K/kg media. The effects on accumulation of nutrients in plants and nutrient residual availability in media were complex and were related to factors such as total plant growth and interactions of nutrients with one another with respect to availability for absorption by plants.