The role of Soluble Sulfate Potassium including zinc-chelate in increasing yield and reducing water consumption in wheat in Kahnoj region–Kerman

Wheat (Triticum aestivum L.) plays a major role in providing the calories and protein needed by the people, and its production strengthens the country’s economic infrastructure.
Among the agricultural factors, optimal plant nutrition has a significant role in increasing the wheat yield per hectare and its quality. In order to investigate the Optimal wheat yield, The effect of Balanced fertilization and the role of Potassium and Zinc fertilizers on increasing yield and reducing water consumption, a field experiment in the form of randomized complete block design with five treatments and three replications was performed in November 2017 in Kahnooj city in Kerman province. The surface area of plots for each treatment was 100 square meters and Chamran 2 wheat cultivar was selected for this study. At first, Soil Analysis were performed before planting. Experimental treatments were: First treatment (control) = All fertilizers consumption except Potassium based ones due to the results of soil analysis including seven times irrigation; The second treatment: Farmers conventional fertilization (NP) including seven times irrigation; Third treatment: first treatment + 300 kg ha-1 Sulfate-Potassium (SOP) before planting including seven times irrigation; Fourth treatment: first treatment + 33% Sulfate-Potassium (SOP) before planting and 67% of the remaining, using Soluble Sulfate Potassium (SSOP) as top dressing including seven times irrigation; Fifth treatment: first treatment + 33% Sulfate-Potassium (SOP) before planting and 67% of the remaining, using Soluble Sulfate-Potassium containing Zn-chelate (SSOP + Zn-EDTA) as top dressing with five times irrigation. Due to heavy winter rainfall and severe flood damage to the farm under test, statistical analysis of the treatments was not possible, however, in the 2019-2020 growing season, this experiment was repeated again in another field where the concentration of Potassium and available Zinc was 86 and 0.34 mg kg-1, respectively. All planting, growing and harvesting operations were carried out regularly according to the custom of farmers in the area. According to the results of this study, it was concluded that a) The Consumption of Potassium and Zinc fertilizers, has significant effect at the level of one and five percent on yield, protein percentage, concentration of Phosphorus, Potassium, Zinc and also, the Phytic acid to Zinc mole ratio (As an index for assessing poor nutrition (PA/Zn)) in grain as well as water use efficiency. b) While the yield and percentage of grain protein in the control treatment was 4648 kg ha-1 and 11.68%, in the second, third, fourth and fifth treatments changed to 4077, 5402, 6137, 6022 kg ha-1 and 8.57, 12.69, 13.62 and 13.85 percent respectively. c) The grain Phytic acid to Zinc (PA/Zn) mole ratio while in the control treatment was 46, in the second, third, fourth and fifth treatments reached to 74, 33, 23 and 21 respectively. D) While the water use efficiency in the control was equal to 0.62 kg/m3, this figure changed in the second, third, fourth and fifth treatments by 0.54, 0.72, 0.82 and 1.11 kg/m3, respectively. The Potassium fertilizers efficiency obtained 2.51 kg kg-1 in the third treatment, whereas, in the fourth treatment this figure improved to 4.96 and in the fifth treatment to 4.58 kg kg-1 respectively. E) Despite the reduction of water consumption from 7560 to 5400 m3 in the fifth treatment compared to other treatments, this parameter in the fifth treatment compared to the control treatment had 31% increase in yield, which was significant at level of one percent. In addition, the concentration of beneficial elements to human health increased. Therefore, the installment application of Potassium and Zinc fertilizers, compared to the one-time application and before planting, while having a significant effect on grain yield and protein percentage, also increased the efficiency and reduced the Phytic acid to Zinc mole ratio to less than 25.

Considering the above results, it can be concluded that in the cultivated soils, if K and Zn concentration are less than critical level, it is necessary to apply K and Zn-fertilizers for obtaining higher yield as well as increase water use efficiency.