Field application of swine (Sus scrofa) slurry provides essential nutrients for crop production. The N to P ratio for slurry is lower than needed by most crops resulting in P accumulation when applied at N rates required for crop growth. Low phytate corn (Zea mays L.) (LPC) contains similar amounts of total P but less phytate P than traditional corn (TC) resulting in improved P bioavailability and reduced P excretion by monogastric animals. While manure from swine-fed LPC diets has a higher N to P ratio than that from TC diets, field studies comparing crop utilization of nutrients from LPC manure have not been conducted. A field study was conducted to compare N and P utilization by no-tillage rainfed sorghum [Sorghum bicolor (L.) Moench.] receiving three annual surface applications of nutrients (inorganic fertilizer, LPC slurry, and TC slurry) and by irrigated corn receiving one incorporated application of nutrients. Sorghum grain and total dry matter N utilization exhibited a year by treatment interaction but total dry matter N utilization was similar for both manure types in all years (61.2 % for TC and 53.8 % for LPC). Grain P utilization was similar for inorganic fertilizer and manure but differed among years (44.4% in 1999, 25.1% in 2000, and 57.0% in 2001). Corn grain N and P utilization did not differ among nutrient sources in the year of application (50.7% for N and 40.4 for P) and increased little in the year following application (62.2 % for N and 50.2 % for P). Crop N and P utilization from LPC manure and TC manure was similar and nutrient guidelines developed for TC swine slurry should also apply for LPC slurry.

PDF provided from Agron. J. 100:4 pp: 997-1004 (2008), with permission, copyright American Society of Agronomy.