گزارش نهایی طرح تعیین حد بحرانی کودهای شیمیایی ‭(N.P.K) ‬برای توتستانهای مختلف استان گیلان

With the aim of bettering Consumption of chemical fertilizers in well being quality and quantity of mulberry leaf and Subsequent to increasing production capacity rural sericultures income level and also controlling environment. This investigation modeled in a four test plots in four zones of Gilan sericulture areas, with four treatments and six repeats. Each repeat contains ten mulberry trees and variable are mixture of chemical fertilizers(urea,Amonium phosphate,Potassium sulphate), keeping ratio 6.3.4. between N.P.K' elements. Amounts of treatment, zero gram for controller, 150grm(urea69-Am- phosphate 35grm, potassium sulphate 46 gram), 200 grm(92-46-62),2S0 grm(115-58-77) for three other treatments. Totally for ten trees in base of above amounts for each repeat have calculated(1500 grm-2000 grm-2S00grm),so 60% of these amounts are used in beginning of Spring before rearing and 20% after harvesting and 20 reminded percent in Autumn of the same year. With using Kilt Nelson principle in which the results show that,etTect of chemical fertilizers on operation of element concentrationin of diffirent kinds of soil were diffirent which were due to specification of variable above soils and amounts of nutrient elements aviable in fertilizers. with consumption of chemical fertilizers in most of soils the percentages of operatoin and relative operation were being positive. At last critical level of chemical fertilizers for mulberry fields of Gilan zones for Nitrogen %O.2 and absorbable phosphor15ppm and for potassium 186ppm are detemined.