Phosphorus Uptake by Potato from Biochar Amended with Anaerobic Digested Dairy Manure Effluent

Abstract

Sorption of plant nutrients from dairy storage lagoons by biochar and use as a supplemental fertilizer is a beneficial strategy to reduce nutrient contamination around dairies and supply nutrients to potato (Solanum tuberosum L.) and other crops. This research evaluated potato growth responses and P partitioning from several rates of P applied as either mono‐ammonium phosphate (MAP) or as P recovered from anaerobic digested dairy manure using biochar. Single‐stemmed plants of the potato cultivars Ranger Russet and Umatilla Russet were grown in 7‐L pots containing Quincy sand soil (mixed, mesic Xeric Torripsamment). Biochar amended with dairy effluent applied at 5.7 and 11.4 Mg ha–1 with fertilizer application rates equivalent to 55 and 110 kg P ha–1 maintained adequate P levels in potato petioles of both cultivars through 85 d after planting. Total plant P uptake was greater for treatments receiving MAP. Total potato biomass and tuber yields of Umatilla Russet were 30 and 27% lower when amended with basic or enriched biochar compared to MAP treatments, respectively. Tuber biomass declined 10 and 20% for Ranger Russet and Umatilla Russet for the 11.4 Mg ha–1 amended biochar, respectively compared to MAP fertilized treatments. Similar declines were found for the aboveground biomass and roots. The 5.7 Mg ha–1 of enriched biochar supplied 70 to 80% of the P requirement for potato growth. These findings are an important step in providing evidence of the benefits of using recovered P as a fertilizer supplement to reduce the reliance on rock phosphates.