Comparison of Nutrient and Metal Loadings with the Application of Swine Manure Slurries and Their Liquid Separates to Soils

• Published in: Journal of environmental quality Vol. 45; no. 5; pp. 1769 - 1775
• Main Authors: Kumaragamage, D., Akinremi, O. O., Racz, G. J.
• Format: Journal Article
• Language: English
• Published: United States The American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc 01.09.2016
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2016.04.0130

The accumulation of phosphorus (P) and metals is a serious concern with the continuous application of manure to agricultural soils. Solid–liquid separation of swine slurry is a promising approach to reduce P and metal loadings through application of separated liquid (SL) as a nutrient source. However, little information is available on nutrient and metal loadings with the application of SL compared with unseparated raw manure (RM). We analyzed element concentrations and calculated nutrient and metal loadings for RM and their respective SL applications, considering an application rate of 100 kg total nitrogen (N) ha−1. Samples of SL were obtained through three separation techniques: (i) centrifugation without a flocculant, (ii) centrifugation with a flocculant, and (iii) rotary press with a flocculant. Irrespective of separation technique, calculated P loadings with the application of SL were only 50 to 70% of that of RM at equivalent rates of total N yet exceeded crop removal rate. In contrast, calculated K and Na loadings with SL application were significantly greater than with RM, indicating a possible build‐up of K and Na in soil. Calculated Ca and Mg loadings were significantly greater with RM than with SL. Loadings of Al, As, Ba, Cd, Cr, Fe, Mn, Ni, Pb, Sn, Se, Ti, and V were low, whereas Cu and Zn loadings were above crop removal rates for RM and SL. For solid–liquid separation to provide a lasting solution to the problem of P and metal accumulation, the SL must be supplemented with commercial N fertilizer to meet crop N demand. Core Ideas P loading with SL was only 50 to 70% of that of swine slurry applied at equivalent rate of N. Loadings of K and Na with SL were higher, indicating a possible salt build‐up in soil. Cu and Zn loading with application of swine slurry and SL were above crop removal rates. Loadings of other trace metals were low with both SL and raw swine slurry application.