Polyhalite improves growth, yield, and quality and reduces insect pest incidence in sugarcane (Saccharum officinarum L.) in the semiarid tropics

Introduction In semiarid tropical locations, polyhalite (K 2 Ca 2 Mg(SO 4 )4H 2 O) and muriate potash (KCl) were tested for their ability to increase cane growth, yield, and recovery at potash (K)- and calcium (Ca)-deficient sites. Methods The treatments involved control plots with no potash fertilizer (T 1 ); T 2 and T 3 applied potassium through (muriate potash) MOP only at 80 and 120 kg K 2 O ha −1 , whereas T 4 and T 5 applied potassium with half of MOP and polyhalite at 80 and 120 kg K 2 O ha −1 , respectively. Results and discussion At 35 days after harvest (DAH), T 2 (10.82%), T 3 (24.1%), T 4 (34.9%), and T 5 (34.9%) had a greater ratoon resprouting rate than did the control treatment, where it was just 37.0 out of 100 harvested canes. At 308 DAH, T 2 (−5.9%), T 3 (−5.7%), and T 5 (−6.6%) presented greater leaf chlorophyll contents than did T 1 . The K-fertilized plots yielded 64.31 t ha −1 in T 2 and 65.97 t ha −1 in T 5 , whereas the control plot yielded 61.5 t ha −1 . Compared with the control plots, the T 5 plots experienced fewer stalk borer (−28.6%), top borer (−23.3%), and early shoot borer (−23.3%) attacks. T 2 , T 4 , and T 5 presented higher percentages of commercial cane sugar (CCS) (6.82, 8.83, and 8.74%, respectively) than did the control plots. T 1 and T 3 had similar CCSs (10.99 and 11.33%, respectively). The CCS weight per area ranged from 7.98 to 8.47 t ha −1 near maturity. T 4 (8.59 t ha −1 ) and T 5 (8.60 t ha −1 ) had significantly greater values than did T 1 –T 3 . Compared with the control, the applied potassium fertilizer increased the economic output by 8,711, 11,687, 13,485, and 13,857 INR ha −1 in the T 2 , T 3 , T 4 , and T 5 plots, respectively. The higher cost of polyhalite than MOP has reduced its economic advantages. Thus, the T 4 plots outperformed the other treatments in terms of growth, yield, and quality indices, but their higher values (120 kg K 2 O ha −1 ) were statistically equivalent. Conclusion Finally, the study concluded that MOP and polyhalite at a 50% ratio of 80 kg K 2 O ha −1 may help improve sugarcane growth, yield, and quality in semiarid tropical locations.