The effect of potassium and zinc fertilizer sources on the quantitative and qualitative yield of dryland chickpeas in different tillage systems

Introduction:
After wheat and rice, legumes are one of the most important agricultural products that are used to feed the people of the world. The amount of protein in legumes is about twice that of cereals, and it is a good quality protein source that complements grain protein. Among the legumes, chickpea (Cicer arietinum L) with 17-24% protein and 40-50% starch and a significant amount of iron, phosphorus and many vitamins, is one of the legumes that has a significant amount of protein and a major contribution to the human diet especially the majority of people with low income (Majnoon Hosseini, 2017). Despite the importance of the chickpea crop, few studies have been conducted on the application of micronutrients. Proper fertilization is one of the techniques that is expected to be effective in increasing the yield of this crop per unit area and the quality of this crop (Aktas, 2009). It has been reported that at least 30 to 50 percent of the crop yield was related to the optimal use of fertilizers (Heisey & Norton, 2007). The optimal consumption of nutrients for the optimal production of crops varies depending on the type of soil in the region and agricultural operations, therefore, in case of changing the tillage method, it is necessary to choose a fertilizer formula that is compatible with the tillage method.

Materials and Methods:This research was carried out as a split plot in the form of a randomized complete block design in 3 replications. Experimental treatments included tillage methods in 3 levels including conventional tillage (CT), minimum tillage (MT) and no-tillage (NT) in the main plots, and treatments of foliar application were in sub-plots including no foliar application and foliar application of potassium Phosphite liquid fertilizers, K-Amino chelate and Zn-amino chelate (one liter per hectare) and zinc chelate fertilizer( with a concentration of 1.5 per thousand) were in the sub-plots. In this project, Mansour chickpea cultivar were planted with a density of 35 seeds per square meter at a depth of 5-7 cm and mechanized by a direct seeding machine (ASKE 2200) between November 15 and December 15 every year. Foliar spraying of fertilizer treatments was done before flowering using a back sprayer. At the end of the growth period in July, 10 plants were harvested in each plot and indicators such as plant height, number of pods per plant, hundred seed weight, seed yield, and biological yield were measured.

Results&Discussion:
The results showed that the effect of tillage on the measured indicators was not significant. However, the highest seed yield (532.6 kg ha-1) was obtained from the no-tillage treatment, which was compared to the Minimum tillage treatments with a seed yield of 497.6 kg ha-1 and Conventional tillage with a seed yield of 412.6 kg ha-1, respectively 7 and 29 the percentage showed an increase. The effect of different fertilizer sources on seed yield, biological yield and plant height was significant at 5% level. All foliar treatments had a significant difference with the control at the 5% level. The highest seed yield was obtained from potassium phosphite treatment with a yield rate of 539.9 kg ha-1. The highest amount of protein was obtained from the Minimum tillage treatment at the rate of 20.35%, the highest amount of phosphorus was obtained jointly from the Minimum tillage and no-tillage treatments at the rate of 57%, and the highest amount of zinc was obtained from the traditional tillage treatment at the rate of 55.33 mg/kg. The effect of fertilizer type on protein, phosphorus and zinc levels was significant at the level of 1 percent (P<0.01). In all cases, the lowest amount was related to the control treatment.

Conclusion:
In order to increase the yield of dryland chickpeas, direct cultivation (no tillage) along with foliar spraying of fertilizers containing potassium and zinc can be useful. In this case, in addition to increasing the production per unit area, it is possible to reduce the costs of fuel and tools caused by the traffic of tillers and to improve the quality of dryland chickpea seeds in terms of protein and zinc.