Response of Ipomoea Batatas (L.) Lam. To Soil Fertilization with Filter Cake‪.‬

ABSTRACT Filter cake is a waste product from sugarcane (Saccharum officinarum L.) processing. Filter cake is often found as a waste product near locations of sugar mills. Currently, sweetpotato [Ipomoea batatas (L.) Lam.] farmers do not use filter cake as fertilizer. If the benefits of filter cake as a soil-improvement material for sweetpotato could be demonstrated, sweetpotato farmers could obtain and use this waste product. Five soil-improvement materials (no filter cake; 10,000 kg [ha.sup.-1] filter cake; 20,000 kg [ha.sup.-1] filter cake; 40,000 kg [ha.sup.-1] filter cake; and 600 kg [ha.sup.-1] compound fertilizer) were assessed in a randomized complete block design that was replicated five times. The objective of this study was to assess the influence of filter cake on yield and yield components of sweetpotato, soil temperature, and weed infestation. Results showed that yields were highest (13,427.4 kg [ha.sup.-1]) with 10,000 kg [ha.sup.-1] of filter cake application, and lowest (11,686.0 kg [ha.sup.-1]) with 40,000 kg [ha.sup.-1]. Mass of tuber/plant made 28.1% (r = 0.530; n = 25) contribution to increased yield; tuber length contributed 3.5% (r = 0.186; n = 25) to yield. Weed infestation was negatively, but non-significantly correlated (r = -0.161; n = 25) with storage root yield. Soil temperatures did not significantly vary among the treatments, though 5-cm depth temperatures were higher than temperatures at 10-cm depth and soil surface. Based upon the results of this experiment, it is recommended that 10,000 kg [ha.sup.-1] of filter cake be applied to sweetpotato.