Effects Of Controlled-Release Fertilizers Coating Residue On Soil Physical And Chemical Property And Growth Of Vegetable

The nutrient release rate of Controlled Release Fertilizer (CRF for short)was accordant with plant nutrient absorption, and Controlled Release Fertilizercould improve the use efficiency of fertilizer. In this paper, Controlled ReleaseFertilizers were conducted in middle demonstrated workshop sponsored byagricultural technological span planed item of agricultural ministry. Release inwater experiment, residual coating decomposed experiment; cole and lettucepotted experiment and together with method of chemical analysis have beenused in the paper. The purpose of this paper was: 1) to study effects of CRFSresidual coating on soil physical and chemical property and biological activityof vegetable; 2) to illustrate effects of CRFS residual coating on soilenvironment and plants. As a result, this paper could provide academicguidance for further exploitation and extending and application of CRF, and sothat more vegetable CRFS could be provided. Main results were as followed:1. The nutrient release curve of CRFs in water showed a shape ofparabola or "S". Three release stages were found in CRFs releasing curve.Release rate increased with time in the first stage, then released at summitstage and decreased with time in the third stage. The rate of the nutrientreleased at summit stage between the two stages could match plant nutrientneeding in maturation.2. Effects of residual coating on soil physical and chemical property: thesoil bulk density decreased and the total porosity increased obviously with theincrease of controlled release fertilizers residual coating. So aerated status ofsoil has been improved and loose soil increased the aerated and dank characterof soil. Besides, leftover in soil of coating could reduce and therefore decreasethe bad influence of soil to some extent. As a result, CRF and residual coatingcould provide steady pH and EC for vegetable, and increase nutrient content ofsoil, which was favorable for the growth of cole and lettuce. 3. Effects of residual coating on soil water: the pH of soil water in CRFand CRFRC treatments was kept at 7.0 around and has little change duringgrowth period of lettuce. Because CRF nutrient could release slowly andwater-solubility salt in soil water could not accumulate rapidly in short time,which improved the safety of seed burgeoning and pullulating. Besides, thenutrient release rate of Controlled Release Fertilizer was in accordant withgrowth character of cole and lettuce, providing the best nutrient supply, so thatthe need of growing could be satisfied.4. Effects of residual coating on growing quality of vegetable: Owing toconstant supply of CRF nutrients the nutrient absorption of plants hasimproved. The plant height, contents of chlorophyll, number of leaves, leafarea and growth potential of the cole and lettuce had been increased obviouslywith the addition of residual coating content. As a result, the biology yield hadincreased.5. Effects of CRF and residual coating on nutrient content of vegetable:Owing to constant supply of CRF nutrients, content of plants' nutrient hadimproved. The vegetable total nitrogen content of treatments CRFRC1,CRFRC2, CRFRC3, CRF1 and CRF2 had increased by 1 to 2 times, comparedwith CK. The vegetable total phosphorus content of treatments CRFRC1,CRFRC2 and CRFRC3 had increased by 1 to 4 times, compared with CK.Besides, the vegetable total potassium content of treatment CRFRC3 washighest.6. Effects of CRF and residual coating on quality of vegetable: Theexperiment indicated that, the reductive Vc content, Soluble Sugar content andthe ratio of sugar to acid of cole and lettuce had been increased with theapplication of CRF residual MDA content of letce could decrease significantly.So the quality of the vegetables could be improved evidently by using CRFand residual coating. And thus improve the economic value.