Applications of aluminum sulfate (AIz(SO4)3 ¯ 14H20), commonly referred to as alum, to poultry litter have been shown to decrease P runoff from lands fertilized with litter and to inhibit NH3 volatilization. The objectives of this study were to evaluate the effects of alum applications in commercial broiler houses on: (i) NH3 volatilization (inhouse), (ii) poultry production, (iii) litter chemistry, (iv)runof f following litter application. Two farms were used for this study: one had six poultry houses and the other had four. The litter in half of the houses at each farm was treated with alum; the other houses were controls. Alum was applied at a rate of 1816 kg/house, which corresponded to 0.091 kg/bird. Each year the houses were cleaned in the spring and the litter was broadcast onto paired watersheds in tall fescue at each farm. Results from this study showed that alum applications lowered the litter pH, particularly during the first 3 to 4 wk of each growout. Reductions in litter pH resulted in less NHṽ olatilization, which led to reductions in atmospheric NH~ in the alumtreated houses. Broilers grown on alum-treated litter were significantly heavier than controls (1.73 kg vs. 1.66 kg). Soluble reactive phosphorus (SRP) concentrations in runoff from pastures fertilized with alumtreated litter averaged 73% lower than that from normal litter throughout a 3-yr period. These results indicate that alum-treatment of poultry litter is a very effective best management practice that reduces nonpoint source pollution while it increases agricultural productivity. p IOULTRY LITTER APPLICATIONS to pastures have been shown to result in relatively high P runoff, even when litter is applied at recommended rates (Edwards and Daniel, 1993). Most of the P in the runoff is in the soluble form (Edwards and Daniel, 1993), which is the form most available for algal uptake (Sonzogni et al., 1982). Concerns have arisen over this, since P is normally the limiting nutrient for eutrophication (Schindlet, 1977). Recent research has shown that alum additions to poultry litter can decrease P solubility in the litter by orders of magnitude (Moore and Miller, 1994). Shreve et al. (1995) found that P runoff from tall rescue (Festuca arundinacea Schreb.) plots fertilized with alum-treated litter was 87% lower than plots fertilized with normal litter. The rescue plots receiving alum-treated litter had significantly higher yields and higher N contents than normal litter, indicating that alum had increased N availability in the litter. We hypothesized that the increase in N availability was due to a decrease in NH3 volatilization. This was confirmed in laboratory studies conducted by Moore et al. (1995, 1996), which showed alum amendments to poultry litter could reduce NH3 volatilization losses by as much as 99%, compared with normal litter.

No abstract

Arkansas produces approximately one billion broilers (Gallus gallus domesticus) each year. Phosphorous runoff from fields receiving poultry fitter is believed to be one of the p~mary factors affecting water quality in northwest Arkansas. Poultry Htter contains =20 g P kg-~, of which-2 g P kg-~ is water soluble. The objective of this study was to determine if soluble P levels could be reduced in poultry Htter with AI, Ca, and/or Fe amendments. Poultry Htter was amended with alum, sodium aluminate, quick lime, slaked lime, ealcitic limestone, dolomitic limestone, gypsmn, ferrous chloride, ferric chloride, ferrous sulfate, and ferric sulfate, and incubated in the dark at 25 °C for 1 wk. The Ca treatments were tested with and without CaF2 additions in an attempt to precipirate fluorapatite. At the end of the incubation period, the fitter was extracted with deionized water and water soluble P determined. Water soluble P levels in the poultry litter were reduced from >2,000 mg P kg-x litter to <1 mg P kg-[ litter with the addition of alum, quick lime, slaked lime, ferrous chloride, ferric chloride, ferrous sulfate, and ferric sulfate under favorable pH conditions. Gypsum and sodium aluminate reduced water soluble P levels by 50 to 60%. Calcitic and dolomitic limestone were less effective. The results of this study suggest that treating litter prior to field application with some of these compounds could significantly reduce the amount of soluble P in runoff from Htter-amended pastures. Therefore, chemical additions to reduce soluble P in Htter may be a best management practice in situations where eutrophication of adjacent water bodies due to P runoff has been identified. Preliminary calculations indicate that this practice may be economically feasible. More research is needed, however, to determine any beneficial and/or detrimental aspects of this practice.

can greatly exacerbate runoff P losses (Kleinman, 2000; Sharpley et al., 1998), most states have adopted or are Water-extractable P (WEP) in manure is correlated with P concenin various stages of developing site assessment indices tration in runoff from soils amended with manure and is, thus, an effective indicator of environmental P loss. This study sought to eluci-that distinguish between mineral and manure sources date methodological factors affecting WEP measurement in manure of P on the basis of P availability to runoff water (Weld and to quantify errors related to two established methods of manure et al., 2000). These indices are a component of a national WEP measurement. Dairy cow (Bos taurus) manure, poultry (Gallus strategy to develop Comprehensive Nutrient Managegallus domesticus L.) (layer) manure, and swine (Sus scrofa domestica ment Plans that considers P impacts and utilization for L.) slurry were used. Varying dry matter/distilled water ratios (1 to animal feeding operations (USDA and USEPA, 1999). 20:200) revealed that greater dilution of manure dry matter increased Soil and manure P solubility in water likely controls WEP (mean 1.8-5.4 g kg Ϫ1), likely because of the dissolution of DRP concentrations in runoff (McDowell and Sharpley, calcium phosphates. Increasing shaking time from 1 min to 24 h, 2001a). For instance, Pote et al. (1999) found that DRP increased manure WEP concentration (average 3.7-8.2 g kg Ϫ1). Filtraconcentrations in surface runoff were closely related tion with Whatman 1 paper filters resulted in significantly higher WEP measurements in dairy and poultry manure (4.1 g kg Ϫ1) than to WEP concentrations in three acidic soils. Because with a 0.45-m filtration (3.7 g kg Ϫ1). No significant difference was manure application to soils results in large, temporary observed in the swine slurry. A rainfall-runoff experiment using simuincreases in WEP at the soil surface, the zone that serves lated rainfall was conducted to determine the effect of the individual as the source of P in runoff, forms of P added to soil factors on predicting dissolved-reactive P (DRP) concentration in directly affect P availability to runoff. Moore et al. runoff. Comparison of regression coefficients relating manure WEP (2000) reported significant differences in DRP concento runoff DRP concentration revealed an optimum shaking time betrations in runoff from pastures amended with either tween 30 min and 2 h, but did not support any single manure/distilled alum-treated or untreated poultry litter. They observed water ratio or filtration method. Replication of two established methconcomitant decreases in the WEP fraction of poultry ods of manure WEP measurement resulted in coefficients of variation litter treated with alum and runoff DRP concentrations of 0.01 to 0.12. Results of this study support the use of a single method with a fixed manure/distilled water ratio for liquid and dry manures.

Field applications of poultry litter at rates to meet forage N requirements normally result in an over‐application of P. Chemical amendments have the potential to reduce the solubility of manure P through precipitation and/or adsorption reactions. This study was conducted to determine the effects of two chemical amendments, alum (Al2 (SO4)3 · 14H2O) and ferrous sulfate (FeSO4 · 7H2O), on P concentrations and load in runoff and to evaluate the effects of amended litter on forage production. Litter was broadcast applied to fescue (Festuca arundinacea Schreb.) plots at 11.2 Mg ha−1 alone and in combination with alum or ferrous sulfate (1:5 amendment/litter). Rainfall simulators were used to produce three runoff events at 2, 9, and 16 d after litter application. Alum reduced the P concentrations in runoff by 87 and 63% of that from litter alone for the first and second runoff events, respectively, whereas ferrous sulfate decreased runoff P concentration by 77 and 48%, respectively. Both chemical amendments resulted in significant reductions (P < 0.05) in total P load for the first runoff event. Litter application significantly increased fescue yields, with total forage yield having the greatest response to alum‐amended litter. Mean forage yield with alum amended litter was 2358 kg ha−1, compared with a mean yield of 1847 kg ha−1 with litter alone. This was probably due to decreased NH3 volatilization with the alum treatment. The combination of decreased P loss and increased forage yields suggest that alum‐amended litter has substantial promise for use as an environmental and economic management tool in the poultry industry.