Effect of Biochar on the Yield of Potatoes Cultivated Under Wastewater Irrigation for Two Seasons

Abstract

This study investigated the effects of biochar, produced from plantain peel, on the yield of potatoes (Solanum tuberosum L.) irrigated with wastewater in two consecutive seasons. Potatoes were grown in 2015 and 2016 in nine lysimeters (1.0 m × 0.45 m), packed with sandy soil to a bulk density of 1.35 Mg m−3. The lysimeters were arranged in a completely randomized design with three replicates. The treatments were (i) wastewater with biochar, (ii) wastewater without biochar, and (iii) freshwater without biochar. The soil with biochar treatments was amended in 2015 with an application rate of 1% (w/w) on the top 0.1 m of soil. After 33 days of planting, the potatoes were irrigated 8 times, on a 10-day irrigation interval, with freshwater or wastewater that was synthesized to represent a typical wastewater in developing countries. Plant health parameters (e.g., photosynthetic rate) were measured. After 120 days of planting, the potato tubers were harvested; the fresh weight was measured and the tubers were counted. The plant health parameters (e.g., photosynthesis rate) varied with time but were not affected by biochar amendment. Also, the total fresh tuber weights as well as the total number of tubers were similar in all treatments although the biochar showed a significant positive effect (p < 0.05) on the pH and the cation exchange capacity of the soil. Thus, it was concluded that application of the plantain peel biochar as soil amendment showed no significant effect on the yield of potatoes irrigated with wastewater.