Swine (Sus scrofa domesticus) waste can be a nutrient source for crops when applied as a manure slurry or lagoon effluent. Limited land area for disposal may result in high application rates. Yet rates must be controlled to ensure stand persistence if perennial crops are grown and if groundwater quality (NO3 concentrations) are to be considered. Also, safe concentration of elements in the resulting forage must be assured if used for animal feed. A 4-yr study was conducted to determine the effect of applying swine waste as manure slurry or lagoon effluent on persistence of a temperate forage mixture of predominantly tall fescue (Festuca arundinacea Schreb.). Treatments were: a commercial N-P-K fertilizer (F), consisting of 201 kg/N/ha/yr (67 kg/ha in three applications) and 34 and 65 kg/ha of P and K, respectively; 670 kg of N/ha/yr as a swine manure slurry (M); and supplying approximately 600 (E1) and 1200 (E2) kg of N/ha from swine lagoon effluent. Subtropical grasses invaded all treatments by the third year but the E2 treatment had greatest infestation averaging 53% of the dry matter and tall fescue averaging only 39%. Dry matter yields were similar between F and M treatments averaging 7750 kg/ha/yr while applying N as effluent (E1) increased yields 3430 kg/ha above M. Doubling the N loading rate (E2 vs. E1) did not increase yields (P < or = 0.05). Concentrations of the 11 elements analyzed (N, P, K, Ca, Mg, Cl, Mn, Cu, Zn, Fe, and Na) showed a treatment x year interaction. Forage Zn was consistently increased by M treatment compared with F or E1 treatments and forage Cu was elevated by M treatment the last 2 yr of the study. In vitro dry matter disappearance was similar (670-685 g/kg) among all treatments, but forage NO3-N concentration from E1 and E2 treatments, and after the second year for the M treatment, was considered unsafe for ruminants (> 700 mg NO3-N/kg). The M, E1, and E2 treatments added large quantities of elements (N, P, K, Ca, Na, and Cl) that were not removed in the forage.
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