Effects Of Controlled-Release Fertilizers On Growth Of Three Kinds Of Flowers And Soil Biochemical Characteristics

The application of controlled-release fertilizer which could protect the environment meets the sustainable development of agriculture. Studies showed that nutrient release of Controlled-Release Fertilizers (CRFs) was accordant with plant uptake of nutrients, contributing to enhancing nutrient use efficiency.Some CRF types used in this study were manufactured in middle demonstrated workshop of Shandong Agricultural University, funded by agricultural technology span program sponsored by Ministry of Agriculture; others were from Shandong Kingenta Engineering Co., Ltd. Five experiments including CRF nutrients release experiment in different media, Pot experiment of calla in soilless media; Chinese hibiscus pot experiment and Sedum Aizoon L. field plot experiment were conducted to study the effects of CRFs on the growth, nutrients uptake of flowers and leaching loss rate of nutrients, as well as dynamic changes of nutrient and enzymatic activity in soil. In addition, the optimum application amount of CRFs was accordingly determined, which provided the theoretical support and technical reference for the application of CRFs in varieties of flowers, economically and reasonably. Main results were summarized as follows:1. CRFs release characteristics in different medium had similar nutrient release patterns, but different release rate. The accumulative nutrient release curves of nitrogen (N) in water showed curve of"S"and could be divided into three stages, slow release period, peak period, and decreased period. Nutrient release rate steadily increased with time in the first stage and decreased in the third stage. The nutrients released in the second period reached a summit and satisfied the demanding for nutrients of plants for burgeoning and maturing. Because the index of active N in slow release fertilizer was low, the great mass of N could not release, so the research of menstruating the accumulative N release rate in water needed to be studied further.2. Effects of CRF on nutrients leaching and dynamic change in soil: The content of leaching nitrogen (N) of CRFs was less compared with CCFs, and the loss of high level was more than low level. The minimum leaching phosphorus (P) of Osmocote low level was 0.30%, but the maximum leashing P of CCFs high level was 5.50%. The minimum leaching potassium (K) of KFAs low level was 10.69%, and the quantity was lower than the CCFs. The CRF treatments received better results than CCF, UF and SF treatments by increasing both growth potential and content of NO3--N, NH4+-N, available P and available K. pH value of CRFs in leaching fluctuated 0.04-0.26 and 0.08-0.24 unit during the whole growth periods, in soil fluctuated 0.03-0.04 unit at the same time. In addition, CRF treatments provided a steady EC during the whole growth periods of flowers in leaching and soil.3. Effects of CRF on enzyme activity in soil: Soil urease activity showed the tendency of hoist- reduce- hoist- reduce, and the soil urease activity of CRF1 treatment in the 30th day was furthest low, in the 90th day was tiptop. Meanwhile CRF1 treatment had distinct difference to CRF2 treatment in the 30th day in soil urease activity; soil catalase activity in CCF treatment and CRF1 treatment reached the minimum in the 30th day and 90th day respectively, but soil phosphotase activity reached the maximum. Soil urease activity and soil phosphotase activity changed in CRFs release characteristics was consistent,and Soil urease and soil phosphotase activities had significant positive correlation with available nutrients in soil, but soil catalase activity was in contrast. So soil urease and soil phosphotase activities could be used to indicate the supply of available nutrient and intensity.4. Effects of CRF on growth potential of flowers: Comparing with control and treatments with common compound fertilizer and other treatments, the treatments with CRF had significant effects on the growth potential of flowers. The results showed that the CRF not only promoted the synthesis of chlorophyll in Calla, Chinese hibiscus and Sedum Aizoon L., but also some modal index such as plant height, stem diameter, leaf areas, number of leaves, growth potential, and biomass of plants. Besides, the Chinese hibiscus and Sedum Aizoon L. with CRF treatment possessed boosted florescence, extended view period and increased ornamental value.5. Effects of CRF on nutrient content and biochemical characters of flowers: Field plot experiment showed that content of N and P in leaves reached summit in blooming stage of flower and increased by 65.66% and 1.76 times respectively compared with CK, and then decreased with the withering of the flowers. By contrast, content of K in leaves reached summit in blossom period, and was higher than that of control and treatments with CCF and CK. Compound CRF significantly increased NRA. Compared with control, NRA with CRF treatments was 1.44 times as high as CK treatment; MDA content in CRF treatment. was decreased significantly. Content of gallic acid of Sedum Aizoon L. on CRF treatment was the highest and increased by 40.23% and 58.09% compared with CCF treatment and CK treatment.6. The optimum amount and the position of fertilizers of CRF application: Three treatments with CRF were effective and favorable to the growth of Chinese hibiscus, and the middle level of CRF treatment received the best results. Accordingly, the optimum application amounts for Chinese hibiscus in 20cm×15cm pot was N 3g/pot. The use efficiency of co-suits application treatment was greatest, and losses ratio was the lowest, the growth and quality were the best. The mix application treatment was worse than co-suits application treatment, but was better than surface application treatment. So the co-suits were the best application to flowers.