Response of maize to a novel organic potassium fertilizer developed from fruit and vegetable wastes

High cost of synthetic K fertilizers and their unavailability are the serious risks to sustainable maize production in Pakistan. Hence, to explore the alternate sources of K for maize production, a pot study was conducted to evaluate the efficacy of a novel organic K fertilizer, developed from fruit and vegetable wastes. Six combinations i.e. 00-00 (control), 30-00, 00-30, 30-30, 60-00, 00-60 kg per ha K chemical and organic K fertilizers were applied in completely randomized design (CRD) with three repeats using maize (cv. Akbar) as a test crop. The synthetic K was applied as sulphate of potash and for organic K two different batches of organic fertilizers were prepared and applied at the rate of 300 kg per ha. The crop received recommended doses of nitrogen (150 kg per ha) as urea and phosphorus (75 kg per ha) as diammonium phosphate. The soil under study was heavy in texture, alkaline in nature, free from salinity hazards; low in organic matter and deficient in AB-DTPA extractable. Potassium K nutrition improved various growth traits, K accumulation and biomass production of maize. Higher K application rate (60 kg per ha) was significantly superior than lower K application rate (30 kg per ha). Generally, inorganic K was significantly better than the organic K in improving various traits of maize at both K application rates, except for the shoot diameter, which responded more to organic K (30 kg per ha). The integrated use of K was more effective than all other K treatments in elevating different growth parameters of maize, except length and shoot diameter of maize that were highest at the inorganic K application rate of 60 kg per ha. Hence, the integrated use of K saved 50% of the chemical K fertilizer. Overall, K nutrition enhanced various traits of maize, viz. shoot length (9 to 38%), shoot diameter (35 to 95%), shoot fresh biomass (29 to 79%), shoot dry biomass (44 to 219%), number of leaves plant per ha (7 to 60%), leaf area (14 to 40%) and K concentration (2-fold to 4.6-fold). The study concluded that K application at 60 kg per ha, by integrating 30 kg per ha chemical fertilizer with 30 kg per ha organic fertilizer, improved the growth and biomass production of maize. Further validation of these results is warranted under field condition.