عنوان مقاله [English]
Introduction In recent years, continuous operation and disrespect to crop rotation has caused the destruction of soil organic matter so that organic matter in arid and semiarid areas of the country is at least possible and According to the hazards and contamination of chemical fertilizers usage, need to reduce consumption of these inputs and find ecological methods to provide Nutritive requirements for crops, to maintain and increase soil fertility has felt. One of the these ways is using of the appropriate pre-sowing plants, by backing pre-sowing plants (green manure) in soil causes to increase the carbon and organic matter, total nitrogen and soil fertility that this phenomenon occurred as a result of microbiological processes and it causes to releasing the nutrients for the plants. Therefore, this study aimed to investigate of integrated crop management on characteristics of soil nutrients and nitrogen mineralization during the period after adding the green plants remains was conducted in Karaj.
Materials and Methods This research is performed during growing season 2013-14 at the Agricultural Research Station of Islamic Azad University of Karaj, Iran. The experiment was conducted as a split plot based on a randomized complete block design with four replications. Main factors include pre-sowing treatments in 4 levels (Perko PVH, Buko, Cattle manure and Fallow) and sub factors also included nitrogen levels (120 and 240 and 360 kg ha-1, utilized urea source). Perko PVH and Buko belong to Brassicaceae family that if they back to the soil they can increase the oraganic matter. Pre-sowing of Perko PVH and Buko were planted in middle of March. Pre-sowing plants before that they going to flowerer stem coincide with the end of the vegetative stage, two weeks before the corn planting they was picked from the soil surface and the remains mixed with soil by rotavator machine. In order to apply cattle manure application in intended plots the amount of 7 ton ha-1 was given to the soil before the corn planting. On 6 July 2014 corn planting was done by pneumatic machine. Nitrogen fertilizer in 3 times was separated and as a topdressing form in the amount of 10, 70 and 20 percentage in the five-leaf stage, Stem elongation and tasselling emergence stage Were applied. After harvesting corn silage, Samples randomly from zero to 30 and 30 to 60 cm depths in each plot were taken and mixed together. Soil samples separately were dehumidified by air and were passed from 2 mm sieve. Organic carbon of soil samples by oxidation in the presence of potassium dichromate and concentrated sulfuric acid (Hesse, 1971) and total nitrogen were determined by Kjel (Hesse, 1971 ) and for measuring of soil mineral nitrogen, of samples tested by the 2 mol KCl solution the extraction and ammonium nitrate samples were measured by means of distillation and titration with HCl .Data analyses are done by using SAS (Version 9.1.3) statistic software mean comparison was done using the LSD test at probability level of 5%.
Results and Discussion Analysis of variance illustrated that the effect of pre-sowing on organic carbon, total nitrogen, nitrate nitrogen and soil ammonium nitrogen in 5% probability level was significant, so that in all traits, Perko PVH and Buko were the best treatments than the fallow and animal manure treatments. The effect of nitrogen levels on all traits were significant in 1% probability level, so that by increasing the nitrogen usage, the rate of these traits increased. Interaction between pre-sowing treatments and nitrogen levels on soil organic carbon, total nitrogen, nitrate nitrogen and ammonium nitrogen in the soil were highly significant in 1% probability level; so that Perko PVH pre-sowing treatment and consumption of 360 kg ha-1 nitrogen of urea source, the highest values of these traits created. The highest percentage of soil organic carbon affected by Perko PVH pre-sowing treatment and rate of 360 kg ha-1 nitrogen in a rate of 1.08% and the lowest percentage of soil organic carbon was related to cattle manure treatment and rate of 120 kg ha-1 nitrogen in a rate of 0.58. The highest percentage of total soil nitrogen affected by Perko PVH pre-sowing treatment and rate of 360 kg ha-1 nitrogen in a rate of 0.102% and the lowest percentage of total soil nitrogen was related to cattle manure treatment and rate of 120 and 240 kg ha-1 nitrogen in rates of 0.052 and 0.047.
Conclusions By the results of this study, the effect of integrated crop management with integrated application of organic fertilizers with nitrogen fertilizer, the cause of the soil Chemical properties and soil fertility is increased. Hence the use of organic fertilizers, meanwhile the significant reduction in the use of nitrogen fertilizer can reduce their environmental impacts. The result of study indicated that pre-sowings of Perko PVH and Buko had a positive and significant effect on soil chemical parameters and soil chemical characteristics reaction on pre-sowing yield is different. In general can say that planting the pre-sowing plants and return the remains to soil causing the protection and increasing soil fertility and consequently causing the Increase the quantity and quality of the crop and can be considered as a one way to achieve sustainable agriculture.