Management practices for applying liquid swine manure to minimize surface runoff water pollution and improve crop production can be evaluated by conducting long-term field studies. This article documents results from a six-year (1996-2001) central Iowa field study that evaluated the effects of swine manure application management practices on soil nutrients, organic matter, pH, crop yield, and discusses potential water quality implications. Swine manure management practices included single-rate (SR) and double-rate (DR) nitrogen (N) based application rates (168 and 336 kg N ha(-1), respectively), three timings (fall injection [FI], winter broadcast [WB], and spring injection [SI]), and two methods (broadcast and injection) of liquid swine manure. Analysis of these practices involved comparing levels of residual soil total phosphorus (P) as Bray-1 available P (RSP), residual soil nitrate-nitrogen (RSN), percent organic matter (OM%), pH, carbon: nitrogen (C: N) ratio, and crop yields (kg ha(-1)) in a corn-soybean rotation cropping practice. Manure application rates were based on standard crop-available N levels as applied to corn plots and were adjusted for environmental losses. Soil samples were collected immediately prior to commencing the study and after harvest each year and analyzed for RSP, RSN, OM%, pH, and C:N ratio at selected depths in the top 0.30 m of the soil profile. Deep soil core (0-1.22 m) samples also were collected after harvest in 1996 and 2000 and analyzed for RSN as a function of depth in the soil profile. When averaged over the six project years and manure application times for corn plots, these findings showed that DR application plots had significantly higher accumulation of RSP and RSN (32.6% and 36.5%, respectively) versus SR application plots in the top 0.30 m of the soil profile. The RSP for the SI (38.2%) and WB (32.8%) treatments was significantly higher than for the FI treatment on corn plots. The RSN accumulation also was found to be significantly higher for the SI (33.4%) and WB (17.4%) treatments than for the FI treatment on corn plots. The 0-1.22 m deep soil core analysis indicated a higher RSN accumulation in up to 88% of the 1.22 m soil profile depth range for the DR and SI treatments. When averaged across the six years and application rates, corn yield was significantly higher for SI plots (9,596 kg ha(-1)) versus FI plots (9,236 kg ha(-1)). The reduction in FI plot corn yield results may have been due largely to excessive leaching of nutrients through the soil profile from post-harvest rainfall during the fall-spring duration. Swine manure SI plots with the higher DR application rate produced the highest average corn yield (10,093 kg ha(-1)). When averaged over project years and application times, the SI treatment showed an increase of 4.0% in corn yield over the FI treatment. While there were short-term significant increases in OM% for the SI1 treatment during 1996 and 1997, there were no significant cumulative differences in OM% as well as pH and C:N ratio in the soil profile after six years of N management practices at the study site. Although no manure was applied to soybean plots, residual effects of N management practices using the WB and SI application methods in the DR treatment plots during corn years significantly increased average values of RSP, RSN, and soybean yield.Results of this study indicate that long-term application of higher liquid swine manure rates during winter and spring application times resulted in significantly higher post-harvest accumulation of residual P and N in the soil profile. These results also show that incorporation of swine manure during the spring application time produced significantly higher corn yields compared with fall and winter application times. Overall results suggest that while residual soil P and N content may be significantly higher from spring versus fall manure application times, these nutrient runoff losses and the potential threat to surface water quality may be substantially lower during spring and summer compared with fall and winter due to effects from crop nutrient uptake, microbial activity, leaching, and evapotranspiration during the growing season.

This paper describes the design process and results of four pilot projects on CAFO beef feedlots in Iowa using vegetative treatment systems as an alternative to conventional runoff basins with irrigation. These pilot projects are being monitored for performance by Iowa State University researchers. Design parameters and processes are described as well as some of the preliminary results of the first years monitoring program.

Swine (Sus scrofa) manure is an important source of N for crop production. The processing of manure in an anaerobic digester for biogas production is only a partial manure treatment process and is not designed as a disposal method. However, digestion will alter manure characteristics, and this may affect nutrient availability to crops. The objective of this study was to evaluate the N supply to corn (Zea mays L.) from swine manure before and after anaerobic digestion for biogas production. Raw and digested swine manure were late-fall applied as main plots, with three manure N rates as subplots, and six fertilizer N rates as sub-subplots. Response to manure and fertilizer N was determined through soil inorganic N, plant N status and uptake, and grain yield. After 3 yr of study, results indicated no difference between raw and digested swine manure as a source of N for plant use in the year of application or in the residual year. Equivalence to fertilizer N was the same with both raw and digested swine manure, and varied between years with 100% in 2000, 44% in 2001, and 60% in 2002. These differences are attributed to varying growing seasons and N loss potential from time of late fall manure application compared with the spring-applied fertilizer N. Late fall and early spring soil sampling indicated rapid conversion to NO3 with both sources. Results of this work indicate that digested liquid swine manure can readily supply plant-available N and management for corn production should be the same as with raw swine manure.

Two swine feeding trials were conducted (initial body weight = 47 +/- 2 and 41 +/- 3 kg for Trials 1 and 2, respectively) to evaluate reduced crude protein (CP) and yucca (Yucca schidigera Roezl ex Ortgies) extract-supplemented diets on NH3 emissions. In Trial 1, nine pigs were offered a corn-soybean meal diet (C, 174 g kg(-1) CP), a Lys-supplemented diet (L, 170 g kg(-1) CP), or a 145 g kg(-1) CP diet supplemented with Lys, Met, Thr, and Trp (LMTT). In Trial 2, nine pigs were fed diet L supplemented with 0, 62.5, or 125 mg of yucca extract per kg diet. Each feeding period consisted of a 4-d dietary adjustment followed by 72 h of continuous NH3 measurement. Urine and fecal samples were collected each period. Feeding the LMTT diet reduced (P < 0.05) average daily gain (ADG) and feed efficiency (G:F) compared to diet L. Fecal N concentration decreased with a reduction in dietary CP, but urinary ammonium increased from pigs fed diet LMTT (2.0 g kg(-1), wet basis) compared to those fed diet C (1.1 g kg(-1)) or L (1.0 g kg(-1)). When pigs were fed reduced CP diets NH3 emission rates decreased (2.46, 2.16, and 1.05 mg min(-1) for diets C, L, and LMTT). Yucca had no effect on feed intake, ADG, or G:F. Ammonium and N concentrations of manure and NH3 emission rates did not differ with yucca content. Caution must be executed to maintain animal performance when strategies are implemented to reduce NH3 emissions.

Current Status Odor from Concentrated Animal Feeding Operations (CAFOs) CAFOs affect air quality through emissions of odor, specific odorous gases (odorants), odorcarryingparticulates (including organic, inorganic, and biological particulate matter), andvolatile organic compounds (VOCs). Odor from CAFO sources, as experienced by humans, is the composite of 170 or more specificgases in trace concentrations. Odorous gases of primary concern often include hydrogen sulfide (H2S) and VOCs, includingvolatile fatty acids. Odor research in the field and laboratory has largely focused on measuring concentrations interms of dilutions to threshold (odor units per cubic meter) and odor intensity based on categoryor reference scaling. Emission Characteristics Data on odor/odorant emission rates, flux, and emission factors are seriously lacking. Systematic efforts have not yet been initiated to develop accurate emission factors for odorousgases (VOCs, H2S, etc.) that properly represent CAFOs in the U.S. and are needed to developscience-based permitting and abatement policies. Human Response Odor from CAFOs can cause physiological or psychological health responses with regard to(a) frequently exposed neighbors at high concentrations, and (b) certain people with particularsensitivities for whom the health effects are of greater concern. Current Federal and State Policies Federal and State policies regarding CAFOs primarily have addressed water quality protectionfrom point sources under the Federal Clean Water Act and equivalent state statutes; however,only in a few cases have these policies addressed odor and odorants. Integrated Mitigation Programs Approaches to control odor and odorants include: ration/diet modification, manure treatment,capture/treatment of emitted gases, and enhanced dispersion. Each of these mitigation approachesincludes several specific technologies. A particular CAFO may require implementation of one, two or more approaches in order tomeet the environmental quality demands of the area in which it is located.

Ammonia emitted from manure can have detrimental effects on health, environmental quality, and fertilizer value. The objective of this study was to measure the potential for reduction in ammonia volatilization from swine (Sus scrofa domestica) manure by temperature control, stirring, addition of nitrogen binder (Mohave yucca, Yucca schidigera Roezl ex Ortgies) or urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)], segregation of urine from feces, and pH modification. Swine manure [total solids (TS) = 7.6-11.2%, total Kjeldahl nitrogen (TKN) = 3.3-6.2 g/L, ammonium nitrogen NH(+)(4)-N = 1.0-3.3 g/L] was stored for 24, 48, 72, or 96 h in 2-L polyvinyl chloride vessels. The manure was analyzed to determine pre- and post-storage concentrations of TS and volatile solids (VS), TKN, and NH(+)(4)-N. The concentration of accumulated ammonia N in the vessel headspace (HSAN), post-storage, was measured using grab sample tubes. Headspace NH(3) concentrations were reduced 99.3% by segregation of urine from feces (P < 0.0001). Stirring and NBPT (152 microL/L) increased HSAN concentration (119 and 140%, respectively). Headspace NH(3) concentration increased by 2.7 mg/m(3) for every 1 degree C increase in temperature over 35 degrees C. Slurry NH(+)(4)-N concentrations were reduced by segregation (78.3%) and acidification to pH 5.3 (9.4%), and increased with stirring (4.8%) and increasing temperature (0.06 g/L per 1 degree C increase in temperature over 35 degrees C). Temperature control, urine-feces segregation, and acidification of swine manure are strategies with potential to reduce or slow NH(+)(4)-N formation and NH(3) volatilization.

Proper application of livestock manure to agricultural land converts waste to fertilizer, but relies on knowing thenutrient content of the manure. Manure samples (111 solid poultry layer, 95 solid poultry broiler litter, 39 swine solid hoop,72 beef cattle, 85 swine slurry, and 88 swine liquid lagoon) were collected from farms in three states to investigate thefeasibility and limitations for using near-infrared reflectance spectroscopy (NIRS) to analyze manure nutrients. Spectral datain the near-infrared (NIR) region (1100-2500 nm) from manure samples were correlated with chemical analytical data fromthe same samples using partial least squares regression techniques in conjunction with six mathematical data pretreatments.The best calibration equations were selected on the basis of the smallest standard error of prediction (SEP) and the largestcoefficient of determination (R2) of cross-validation. The ratio (abbreviated as RPD) of the standard deviation (SD) of theconstituent in the sample population to the SEP was used to evaluate the future prediction performance of calibration models.After using the mathematical pretreatments, the R2 values of the one-out cross-validation for total solids (TS), volatile solid(VS), total nitrogen (TN), and ammonia nitrogen (NH3-N) were between 0.80 and 0.97 for all manure samples. The R2 valuesof the one-out cross-validation for minerals ranged from 0.71 to 0.81, 0.50 to 0.78, 0.74 to 0.94, 0.66 to 0.91, 0.73 to 0.91,and 0.70 to 0.90 in poultry solid layer, poultry broiler litter, swine solid hoop, beef cattle, swine liquid lagoon, and swine slurrymanure samples, respectively. The RPD values indicate that NIRS can predict TS, VS, TN, NH3-N, and some minerals inmanures. NIRS has potential to predict some nutrient concentrations in manure rapidly and accurately.

The significant expansion of the U.S. poultry industry has led to questions about the effects of large amounts of poultry manure on the surface and groundwater. These are the final year’s results of a field study on how poultry manure application can affect water supplies.

Greater knowledge of soil phosphorus (P) is needed to develop application recommendations for Iowa farmers. This project provides more data on the topic by addressing both agronomic and water quality issues. Question & Answer Q: How can farmers apply phosphorus to greatest advan­ tage for their operations? A: Variable-rate and deep P placement are two technologies that have great promise for better nutrient management and are becoming more accessible to farmers. The results of this project showed that the main justification for their adoption is to manage P better and not necessarily to increase yield, at least in the short term. Therefore, the producer should carefully consider costs and environmental benefits before adopting these technologies. Another useful result is that farmers should trust the P index and in particular watch for factors that increase risk of P loss with surface runoff. Major efforts should be directed at reducing soil erosion and surface water flow, placing P deep into the soil, and avoiding overly high soil-test P values. High soil-test levels and practices that produce little P loss through tile drainage can have major impacts on P loss and water quality when the risk of soil erosion and surface runoff is high.

The application of Near-infrared reflectance (NIB) spectroscopy in livestock manure samples has been limited by the requirement that each instrument must be individually calibrated. One possible solution to the problem is the transfer of NIR calibrations from one instrument to another. Seventy-two beef cattle feedlot manure samples were collected and scanned through the Foss NIRSystem 6500 (master) and the Foss NIRSystem 5000 (slave) instruments. Calibration equations for analyzing 11 constituents, total solids (TS), volatile solid (VS), total nitrogen (TN), ammonia nitrogen (NH3-N), phosphorus (P), calcium (Ca), potassium (K), sulfur (S), sodium (Na), zinc (Zn) and copper (Cu) of beef cattle feedlot manure samples were built in each instrument by the leave-one-out cross validation using partial least squared (PLS) regression. Three standardization methods including cloning, direct standardization (DS), and piece-wise direct standardization (PDS) were used to transfer the master equations to slave spectra. The 72-sample data set was split into a 30-sample standardization set to generate standardized files and a 42-sample prediction set to test the accuracy of different standardization methods. Results of this study show that the performances of calibrations for two instruments are similar. The standard error of difference (SED) was calculated based on the values of master spectra predicted by the master equations and slave spectra (standardized or not) predicted by the master equations. The SED of the standardized slave spectra was much less than the corresponding SED of the unstandardized slave spectra. The SED of the standardized slave spectra predicted by the master equations were less than the corresponding standard error of prediction (SEP) of master calibration models. This study is a first report to demonstrate that the transfer of manure sample calibrations between instruments was successful. It promises to be a satisfactory alternative to individual instrument calibration.

The time between swine (Sus scrofa) manure application to soil as a crop fertilizer, the first rainfall event, and the frequency of rainfall events should influence leaching potential of fecal pathogens. Soil microcosms were inoculated in the lab with a swine manure isolate of Escherichia coli, strain RS2G, expressing green fluorescent protein, to examine how timing and frequency of rainfall events influences RS2G leaching and survival in soil. Liquid swine manure inoculated with RS2G was applied to intact soil cores (20 cm in diameter x 30 cm long) 4, 8, or 16 d before the first rainfall event (50.8 mm over a 4-h period), and each core received one to three rainfall events. Manure application methods (no-till surface-broadcast, broadcast and incorporated, and tilled before broadcast) had no affect on leaching, although there was greater survival in soils when the manure had been incorporated. Most of the RS2G in the leachate appeared following the first rainfall event and RS2G leaching decreased with increasing time between manure application and the first rainfall, although leachates contained as much as 3.4 to 4.5 log colony forming units (CFU) 100 mL(-1) of RS2G when the first rainfall occurred 16 d after manure application. With increasing frequency of rainfalls there was a decrease in subsequent concentrations of RS2G in the leachate. There was no correlation between leachate RS2G and total coliforms or fecal streptococci concentrations. Soil RS2G numbers were 1 to 10% of the inoculum regardless of the length of time between manure application and the first rainfall. RS2G leaching was mostly influenced by the time between manure application and first rainfall event, and significant leaching and survival in soil was possible even if the first rain occurred 16 d after manure application.

Runoff from Iowa State University's 380 head beef cattle concrete feedlot was treated via solids settling, then soil infiltration followed by a small constructed wetland, and ultimately discharged via a vegetated waterway to a nearby stream. Concentrations and nutrient mass flows were reduced dramatically. The treatment system removed over 97% of the Kjeldahl nitrogen (TKN) and ammonia nitrogen, 94% of total phosphorus, and 93% of total solids. The majority of the water quality improvement occurred during the soil filtration process, while flow through the wetland and a vegetated waterway provided polishing of the filtered effluent. Phosphorus concentrations were monitored in soil profiles in the infiltration area over the five years of the project and no buildup was observed. The passive treatment system can very effectively protect surface water quality below open beef feedlots.

Excessive use of animal manure on agricultural lands can impact the quality, of surface and groundwater resources. A three-year study (1998-2000) was conducted on nine 0.4-ha plots and on six 2.1-m(2) lysimeters to investigate the effect of two nitrogen (N) application rates from laying hen manure and one N application rate from urea ammonium nitrate (UAN) fertilizer on surface and groundwater quality. Experimental treatments included N application rates Of 168 kg-N/ha from UAN fertilizer, and 168 kg-N/ha and 336 kg-N/ha from laying hen manure to corn plots. Subsurface drain and runoff water samples were collected and analyzed for nitrate-nitrogen (NO3-N) and orthophosphate (PO4-P). Results of this study indicate that application of hen manure at 336 kg-N/ha resulted in the highest average NO3-N and PO4-P concentrations in subsurface drain water it? comparison with the application of 168 kg-N/ha from either hen manure or UAN fertilizer. Application of manure at 168 kg-N/ha resulted in significantly lower NO3-N loss with subsurface drain water in comparison with NO3-N loss from the other two N treatments. Manure application at a rate of 336 kg-N/ha resulted in a higher concentration of PO4-P in surface runoff in comparison with manure application rate of 168 kg-N/ha. Application rate of manure had no significant effect on NO3-N concentration in surface runoff water In addition, higher PO4-P losses were observed with surface runoff water in comparison with subsurface drain water The use of manure at both low and high application rates in field plots resulted in significantly higher corn and soybean yields in comparison with the use of UAN fertilizer. Results of this study led to the conclusions that application of hen manure at a lower rate of 168 kg-N/ha can result in higher crop yields and minimal water pollution in comparison with same amount of UAN fertilizer or higher manure application rate.

Appropriate manure application parameters are necessary to maximize nutrient utilization by plants from manure while minimizing water pollution potential. This study focused on the movement of bacteria to receiving tile drains following swine manure application. Specifically, the impacts of different manure application regimes on fecal coliform (FC), Enterococcus (EN), and Escherichia coli (EC) densities in subsurface tile drain water were examined for three years. Manure treatments, including fall, spring, and late winter application at a recommended rate of 168 kg N ha-1 (1X) and at 336 kg N ha-1 (2X) were compared with a non-manure treatment where commercial urea-ammonium nitrate (UAN) was applied. Results indicate that flow-weighted average and maximum observed EN and EC levels in tile water were significantly higher where manure had been applied during late winter at the 2X rate versus the UAN and fall treatments. Levels of FC were highly variable, and the spring injection 1X treatment yielded the highest flow-weighted average and maximum tile water FC levels. Results of this study suggest that manure broadcast onto frozen ground may lead to significantly elevated EN and EC levels in tile water in similar environments, especially when applied in excess of crop nutrient requirements.