Release And Leaching Characteristics Of Controlled Release Fertilizer In Soilless Media And Its Effects On Flowers Growth

The application of controlled release fertilizer which could protect the environment meets the sustainable development of agriculture. Soilless culture technology was widely used in different fields of agricultural production. Research of release characteristic and application of controlled release fertilizer in soilless culture could provide scientific basis for agricultural production and sustainable development.Some controlled release compound fertilizers (CRCF) 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 CRCF nutrient release experiment in different media, Cleome spinosa pot experiments, CRCF nutrient leaching experiment, soilless cultivation experiment of Dracaena sanderiana and Spathiphyllum floribundum were conducted to study the effects of CRCFs on soilless cultivation and biological effects of CCRF on plants, which initially determined the optimum CRF application rate on Cleome spinosa , Dracaena sanderiana and Spathiphyllum floribundum, provided the theoretical support and technical basis for the application of CRCFs. Main results were as followed:CRCFs release characteristics in different medium had similar nutrient release patterns, but different release rate. The accumulative nutrient release curves of nitrogen (N), phosphorous (P) and potassium (K) in water all showed curve of"S"and could be divided into three stages, slow release period, peak period, and decreased period. The characteristic equations of nitrogen release in different CRCFs were identical, and the R2 numerical value of regression equation overtopped 0.96, it indicated that estimation of quasi-conjunction of polynomial function was preferably and regression equation could reflect the nutrient release characteristic of CRCFs perfectly. The content of leaching nitrogen (N) of CRCFs was less compared with CCFs. The leaching nitrogen quantity of CRCFs and CCFs were 260.60mg and 487.43mg respectively. Compared with CCFs , CRCFs was reduced by 46.54%. The maximum leaching phosphorus (P) of CCFs high level in different period was 250.38mg, while the CRCFs were 68.20mg. The quantity of CRCFs was lower 15.30mg than the CCFs. CRCFs could release nutrients consistently during the whole season and the medium didn't have too high of salinity concentration which damage the plants. Accordingly, CRCF provided a secure growth condition for plants in soilless cultivation.EC of CRCFs changed not obvious compared with CCFs. EC of different fertilizers at the same level was related with varieties and release of fertilizers. Plants absorbed nutrient from the solution to meet the requirement of growth.It made the EC of high level of CRCF (14-14-14) was all under the same level of fertilizers.The pH changes tendency of CRCFs were similar in hydroponics of Dracaena sanderiana; it showed the format of ascending, dropping and then ascending. The pH value of CRCFs was down trends .The pH value of solution of Dracaena sanderiana and Spathiphyllum floribundum changed obviously maybe be caused by the mechanism to fit the rhizosphere and the environment.It needed further research. The pH of solution in hydroponics falled down to 4.22 and 2.47 respectively. CRCFs (20-8-10) and (19-6-12) differed in the main forms of nitrogen, so the former pH increased with the increasing volume of fertilizer, the latter represented the opposite trend.Pot experiment of Cleome spinosa showed that some plant growth standards such as plant height, stem diameter, chlorophyll content and etc. CRCF treatments were superior to CCF treatments. The appropriate CRCF (15-15-15) application rate was about 4g·L-1 medium.The maximum root length, root number, root fresh weight and root vigor of controlled release fertilizer had no significant difference compared with NS in Dracaena sanderiana experiment. Root vigor of CRCF (14-14-14) was most active with the root vigor 327.45 ug·g-1·h-1.The reading of SPAD of CRCF (14-14-14) were always the highest throughout the trial.The amount4g·L-1solution CRCF (14-14-14) in Dracaena sanderiana hydroponics experiment was the optimal.