Application of Vinasse and Humic Acid on Soil Potassium Availability and Sugarcane Yield in Conditions of Deficiency of Macro-Elements

Sugarcane, like all sugar plants, has a high need for potassium. However, the long-term addition of chemical fertilizers to agricultural land degrades the physical and chemical properties of the soil. The aim of present study is to investigate the effect of Vinasse and Humic acid on soil potassium concentration and sugarcane yield to reduce recommended fertilizers in the region. This field study was conducted in 2019 as double split plots in the form of randomized complete blocks. Experimental agents include Vinasse at three levels: 0, 50 and 100 cubic meters per hectare, Humic acid at three levels: 0, 2.5 and 5 kg per hectare and fertilizer treatment of high consumption elements at two levels: recommended and 50% recommended. The results showed that the use of Vinasse and Humic acid had a significant effect on the concentration of all soil potassium forms at a probability level of one percent. The results of simple effects showed that the average of exchangeable and soluble potassium in treatments (100m3 Vinasse), (5kg Humic acid) and (recommended fertilizer) were more than the control by 275, 165, 221% and 692, 371, 484% respectively. The interactions of exchangeable and soluble potassium in the composition (100m3 Vinasse, 5 kg of recommended Humic acid and fertilizer) are 384 and 882% higher than the control, respectively. The results showed the highest and lowest yields in (50m3 Vinasse) and (100m3 Vinasse) treatments at the rate of 61.6 and 28.2 tons per hectare, respectively, and the interactions of the highest yield in (50m3 Vinasse, 5 Kg Humic acid and 50% recommended fertilizer) treatment is 75.2 tons per hectare. The results showed that Vinasse and Humic acid can act well as alternatives to chemical fertilizers and reduce the use of chemical fertilizers with proper management.