عنوان مقاله [English]
Lack of attention to the quantity and quality of forage crops led to shortages and low qualities of meat and dairy products. Using cattle manure, plant residues, and green manure increased the dynamic components of the soil. Recently the tendency of farmers toward organic fertilizers have increased due to high costs, demolition of proper soil conditions, environmental consequences and low quality of products produced with chemical fertilizers. It has been reported that combination of manure with chemical fertilizer has increased soil fertility and crop's quality and quantity characteristics due to meeting nutritional needs and increasing the input absorption and use efficiency.
Materials and Methods
In order to assess the effects of different fertilizer sources on maize yield and yield components under different tillage managements, a field experiment was conducted at Zahak Agricultural Research Station for two years (from 2013 to 2014) with a split plot arrangement based on completely randomized block design with three replications. The main plot factors were tillage and no tillage, and sub plot factors were: 1-control, 2-barley green manure without application of fertilizer, 3-barley green manure with application of 100% chemical fertilizer (NPK) to the barley, 4- green manure with 2/3 of chemical fertilizer to the barley and 1/3 to the maize, 5- green manure with 1/3 of chemical fertilizer to the barley and 2/3 to the maize, 6- barley green manure with 50% of animal manure and chemical fertilizer, 7- barley green manure with 40 t.ha-1 of animal manure. The total amount of Nitrogen was measured by digestion method. Likewise, the distillation and titration was tested by using Kjeldahl method. Phosphorus content was measured by a spectrophotometer using colorimetric approach. Potassium content was measured using wet digestion method with salicylic acid and hydrogen peroxide obtained using a photometer movie. The concentration of Zn was measured by atomic absorption. Measurement of grain ash was done through burning and using an electric furnace. Combined variance analysis of data was performed using MSTAT-C statistical software, and the comparison of the means was done at the 5% probability level using Duncan multiple range test.
Results and Discussion
The highest yield was obtained from conventional tillage, 1563 kg.ha-1 more than non-tillage. Fertilizer sources had a significant effect on the concentration of Zn, N, P, K, NDF, grain production, fresh and dry forage production and ash content of the grains. Returning green manure to the soil, along with chemical fertilizer application, not only increased P and N availability in the soil for the next crop, but also simultaneously increased organic matter as well as biological, chemical and physical improvement of the soil properties. The highest (7019 kg.ha-1) and lowest (2097 kg.ha-1) grain yield belonged to T5 and the control treatments, respectively. The highest content of grain ash was observed in the mixed treatment of green manure, cow manure, and chemical fertilizers (1.77%) and its lowest rate was obtained in control (1.125 %). The results showed that addition of cattle and green manure to the soil increased the plant ash, which shows the superiority of these organic manures to chemical fertilizers.
Based on the obtained results of this experiment, it can be inferred that conventional tillage had better effects than no tillage due to its more suitability for soil degrading bacteria cultures, better acceleration of mineralization, and better root growth, resulted in greater access to nutrients and water, and ultimately improving plant growth. During the first year, the root growth limited mainly due to high soil density in the no-tillage treatments. Moreover, because of slow degradation, water and nutrients absorption was low. Due to chemical fertilizer application, nutrient supply was provided faster for the plant. Nevertheless, in long term, it would pollute the surrounding environment and degrade the soil structure. During its converting process in longer period, organic fertilizers provide environmental health and sustainable productivity of the soil; however, consolidated application of organic and chemical fertilizers under a conventional tillage system, support the initial growth, accelerate mineralization, and eventually, increase the uptake of nutrients such as N, P, K, Zn, and Ash content, leads to an increasing yield of maize.