Andy I. Bary

Quantifying benefits associated with land application of organic residuals in Washington State.

This study was conducted to quantify soil C storage, N concentration, available P, and water holding capacity (WHC) across a range of sites in Washington State. Composts or biosolids had been applied to each site either annually at agronomic rates or at a one-time high rate. Site ages ranged from 2 to 18 years. For all but one site sampled, addition of organic amendments resulted in significant increases in soil carbon storage. Rates of carbon storage per dry Mg of amendment ranged from 0.014 (not significant) in a long-term study of turf grass to 0.54 in a commercial orchard. Soils with the lowest initial C levels had the highest rates of amendment carbon storage (r(2) = 0.37, p < 0.001). Excess C stored with use of amendments in comparison with control fields ranged from 8 to 72 Mg ha(-1). For sites with data over time, C content increased or stabilized. Increases in total N were observed at all sites, with increased WHC and available P observed at a majority of sites. Using a 50 Mg ha application rate, benefits of application of biosolids and compost ranged from 7 to 33 Mg C ha. This estimate does not account for yield increases or water conservation savings.

Food Waste Compost Effects on Fertilizer Nitrogen Efficiency, Available Nitrogen, and Tall Fescue Yield

and plant-available N release after compost application to land (Sullivan et al., 1998a). Composting of food waste is increasing as composting technologies Composting transforms organic byproducts into drier, improve and as social and environmental pressures demand alternamore uniform, and more biologically stable products tives to disposal in landfills. Few agronomic studies are available to that can act as slow-release sources of plant-available document N availability following food waste compost application. The objectives of this study were (i) to determine food waste compost N. A high-rate compost application also changes the effects on N fertilizer uptake efficiency across a range of N fertilizer soil physical, chemical, and biological properties that rates, (ii) evaluate the effect of food waste composts on grass yield control N availability for many years following applicaand N uptake by tall fescue (Festuca arundinacea Schreb. ‘A.U. tion (Shiralipour et al., 1992; Dick and McCoy, 1993). Triumph’), and (iii) estimate the residual effects of compost applicaUsually, composts supply only a part of the N needed tion on N fertilizer requirements. We used a split-plot design with to produce high-yielding crops; fertilizer N application two compost treatments and a no-compost control as main plots, and is needed for maximum crop yields. NH4NO3 (34-0-0) applied at rates of 0, 17, 34, 50, and 67 kg ha 1 per Most studies on N availability following compost apgrass harvest as subplots. A food waste yard trimmings paper plication have focused on short-term effects. Composts (FYP) compost and a food waste wood waste sawdust (FW) with C:N ratios above 20:1 may reduce crop production compost were applied at rates of approximately 78 Mg ha 1 (870–1000 kg N ha 1 ) before seeding tall fescue. Compost did not affect grass via microbial immobilization of available N during the yield or N uptake in the first year of the study. Compost increased first year after application (Sims, 1990; Shiralipour et grass yield during the second and third seasons after application. Grass al., 1992). For composts with lower C:N ratios, 0 to 25% N uptake increased linearly with fertilizer N application rate in all of the total N usually becomes plant-available during years. Compost did not affect fertilizer N uptake efficiency (the linear the first year after application (Brinton, 1985; Tester, slope describing grass N uptake vs. fertilizer N application). Nitrogen 1989; Dick and McCoy, 1993). The recalcitrant organic fertilizer requirements during the midseason growth period were recompounds present in mature composts probably interduced by 0.22 to 0.37 kg N ha 1 d 1 during the second season after act less with fertilizer N and organic matter N in soil compost application and by 0.13 to 0.26 kg ha 1 d 1 during the third than do most crop residues. Azam et al. (1985) demonseason after compost application. Results of this study suggest that strated that plant residues high in recalcitrant C are N mineralized from compost and N provided by fertilizer can be considered as additive components of N supply for crop growth. usually less active in immobilization–remineralization transformations in soil than residues containing more labile C. The interaction between compost and the cycling of C of food waste is increasing as compostsoil and fertilizer N has been studied over the short ing technologies improve and as social and enviterm with labeled isotopes and factorial blends of comronmental pressures demand alternatives to disposal in post plus fertilizer N. Sikora and Yakovchenko (1996), landfills. Over 100 food waste composting facilities were using 14C-labeled soil organic matter, found that comactive in the USA in 1999 (Glenn and Goldstein, 1999). post did not increase soil organic matter decomposition. Composting in aerated windrows is becoming a widely They found that addition of soil stimulated a small adopted method for rapid composting of wet, putresciamount of compost decomposition and N mineralizable food waste at large composting facilities (Touart, tion. Paul and Beauchamp (1994) reported immobiliza1999; Sikora and Sullivan, 2000). The bulking agent that tion of fertilizer 15N and a very small amount of net N is used to maintain porosity in aerated windrows plays a mineralization in a 12-wk incubation with composted large role in determining final compost N concentration beef cattle manure. Available N from compost was a reliable substitute for up to 50% of fertilizer N supplied D.M. Sullivan, Dep. of Crop and Soil Science, Oregon State Univ., to tall fescue in growth chamber studies (Sikora, 1998; Corvallis, OR 97331; D.R. Thomas, Dep. of Statistics, Oregon State Sikora and Enkiri, 1999). Univ., Corvallis, OR 97331; A.I. Bary, S.C. Fransen, and C.G. Cogger, Because composts contain stabilized organic matter, Dep. of Crop and Soil Sciences, Washington State Univ., Puyallup, WA 98371. Contribution #11550 from Oregon State Univ. Agric. Exp. Abbreviations: ANR, apparent N recovery by tall fescue for midseaStn. Received 13 Dec. 2000. *Corresponding author (Dan.Sullivan@ son growth period; CEC, cation exchange capacity; FYP, compost orst.edu). derived from mixture of food waste yard trimmings paper; FW, compost derived from mixture of food waste wood waste sawdust. Published in Soil Sci. Soc. Am. J. 66:154–161 (2002).

Nitrogen Availability Seven Years After a High-Rate Food Waste Compost Application

Long-term effects of compost application are expected, but rarely measured. A 7-yr growth trial was conducted to determine nitrogen availability following a one-time compost application. Six food waste composts were produced in a pilot-scale project using two composting methods (aerated static pile and aerated, turned windrow), and three bulking agents (yard trimmings, yard trimmings + mixed paper waste, and wood waste + sawdust). For the growth trial, composts were incorporated into the top 8 to 10 cm of a sandy loam soil at application rates of approximately 155 Mg ha−1 (about 7 yd3 1000 ft2). Tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’) was seeded after compost incorporation, and was harvested 40 times over a 7-yr period. Grass yield and grass N uptake for the compost treatments was greater than that produced without compost at the same fertilizer N rate. The one-time compost application increased grass N uptake by a total of 294 to 527 kg ha−1 during the 7-yr. field experiment. The greatest grass yield response to compost application occurred during the second and third years after compost application, when annual grass N uptake was increased by 93 to 114 kg ha−1 yr−1. Grass yield response to the one-time compost application continued at about the same level for Years 4 through 7, increasing grass N uptake by 42 to 62 kg ha−1 yr−1. Soil mineralizable N tests done at 3 and 6 yr. after application also demonstrated higher N availability with compost. The increase in grass N uptake accounted for 15 to 20% of compost N applied after 7-yr. for food waste composts produced with any of the bulking agents. After 7-yr, increased soil organic matter (total soil C and N) in the compost-amended soil accounted for approximately 18% of compost-C and 33% of compost-N applied. This study confirmed the long-term value of compost amendment for supplying slow-release N for crop growth.

Fertilizer nitrogen replacement value of food residuals composted with yard trimmings, paper or wood wastes

Composting offers an opportunity to recycle food waste as a soil amendment. A three year growth trial was conducted to determine the fertilizer nitrogen (N) replacement value of food waste composts for cool season perennial grass production. Six composts were produced in a pilot-scale project with two composting methods (aerated static pile and aerated, turned windrow). The aerated, turned windrow method simulated “agitated bay” composting systems, which utilize routine mechanical agitation. Compost bulking agents included yard trimmings, yard trimmings + mixed paper waste, and wood waste + sawdust. Finished composts had Kjeldahl N concentrations ranging from 10 to 18 g N/kg. For the growth trial, composts were incorporated into the top eight to 10 cm of a sandy loam soil at application rates of approximately 155 Mg/ha (about 7 yd3/1000 ft2). Tall fescue (Festuca arundinacea Schreb. ‘A.U. Triumph’) was seeded after compost incorporation, and was harvested repeatedly at a late vegetative growth stage (Apri...

Nitrogen contribution of rye–hairy vetch cover crop mixtures to organically grown sweet corn

Organic cropping systems that utilize winter grown cereal–legume cover crop mixtures can increase plant available nitrogen (N) to a subsequent cash crop, but the rate of N release is uncertain due to variations in residue composition and environmental conditions. A study was conducted to evaluate N availability from rye ( Secale cereale L.)–hairy vetch ( Vicia villosa Roth) cover crop mixtures and to measure the response of organically grown sweet corn ( Zea mays L.) to N provided by cover crop mixtures. Nitrogen availability from pure rye, pure hairy vetch, and rye–vetch mixtures was estimated using laboratory incubation with controlled temperature and soil moisture. Sweet corn N response was determined in a 2-year field experiment in western Washington with three cover crop treatments as main plots (50:50 rye–vetch seed mixture planted mid September, planted early October, and none) and four feather meal N rates as subplots (0, 56, 112 and 168 kg available N ha −1 ). Pure hairy vetch and a 75% rye–25% hairy vetch biomass mixture (R 75 V 25 ) released similar amounts of N over 70 days in the laboratory incubation. But, the initial release of N from the (R 75 V 25 ) treatment was nearly 70% lower, which may result in N release that is better timed with crop uptake. Cover crops in the field were dominated by rye and contained 34–76 kg ha −1 total N with C:N ranging from 18 to 27. Although time of planting and management of cover crop quality improved N uptake in sweet corn, cover crops provided only supplemental plant available N in this system.

Biosolids applications to tall fescue have long-term influence on soil nitrogen, carbon, and phosphorus.

Repeated applications of biosolids provide long-term benefits by increasing soil organic matter and N supply but can cause excess accumulation of P. Our objective was to determine the residual effects of repeated surface applications of biosolids on N availability and fate, tall fescue ( Schreb.) response, soil C, and P. A field experiment was started in 1993 to compare two biosolids products, each applied at three rates (6.7, 13.4, and 20.1 Mg ha yr), with synthetic N fertilizer (0 and 403 kg N ha yr as ammonium nitrate). Treatments were surface applied for 10 yr, followed by a 9-yr residual period where all plots received a reduced rate of inorganic N (202 kg N ha yr). Annual measurements included forage yield, N uptake, and soil nitrate N. Soil samples collected in 2002 and 2011 were analyzed for total C and N and Bray-1 P. Cumulative apparent N recoveries in harvested grass (1993-2010) were 51% for biosolids N and 72% for ammonium nitrate. Net fall soil nitrate N summed for the period 1993-2002 ranged from <1 to 3% of N applied. The N applied that was accounted for in forage and soil averaged 74% for biosolids and 73% for ammonium nitrate. Soil C increased in the biosolids treatments, and the increase was equivalent to 27% of biosolids C. Bray-1 P remained at excessive levels (338-629 mg P kg soil) 9 yr after the last biosolids application.

Long-Term Crop and Soil Response to Biosolids Applications in Dryland Wheat

Biosolids have the potential to improve degraded soils in grain-fallow rotations. Our objectives were to determine if repeated biosolids applications in wheat ( L.)-fallow could supply adequate but not excessive N for grain production and increase soil C without creating a high risk of P loss. A replicated on-farm experiment was established in 1994 in central Washington, comparing anaerobically digested biosolids with anhydrous NH and a zero-N control. Biosolids were applied at 5, 7, and 9 Mg ha every fourth year through 2010 and incorporated 10 cm deep, while anhydrous NH plots received 56 kg ha N every second year. Grain yield and protein were determined. Soil chemical, biological, and bulk density analyses were made in 2012. Medium and high biosolids rates significantly increased grain yield (3.63 vs. 3.13 Mg ha) and protein (103 vs. 85 g kg) compared with anhydrous NH averaged across all crops. The medium biosolids rate had significantly lower bulk density (1.05 vs. 1.22 g kg) and greater total C (0-10-cm depth) (16.9 vs. 9.4 g kg), mineralizable N (156 vs. 52 mg kg), and extractable P (114 vs. 16 mg kg) than anhydrous NH. The P index site vulnerability increased from low for anhydrous NH to medium for the biosolids treatments. Soil NO-N was nearly always <10 mg N kg soil (0-30-cm depth). Medium and high biosolids rates significantly increased bacteria/fungi ratios, Gram-negative bacteria, and anaerobic bacteria markers compared with anhydrous NH. Biosolids can be an agronomically and environmentally sound management practice in wheat-fallow systems.

Validation of a 2 Percent Lactic Acid Antimicrobial Rinse for Mobile Poultry Slaughter Operations

Poultry processing antimicrobial interventions are critical for pathogen control, and organic, mobile operations in Washington seek alternatives to chlorine. Laboratory and field studies (three replications each) evaluated lactic acid efficacy as a chlorine alternative. For the laboratory study, retail-purchased, conventionally processed chicken wings inoculated with Salmonella were randomly assigned to the following treatments: Salmonella inoculation followed by no treatment (10 wings) or by 3-min rinses of water, 50 to 100 ppm of chlorine, or 2% lactic acid (20 wings for each rinse treatment). Wings were sampled for Salmonella enumeration on xylose lysine desoxycholate agar. During pastured poultry processing at mobile slaughter units for each field study replication, 20 chicken carcasses were randomly assigned to each treatment: untreated control or 3-min immersion in lactic acid or chlorine. Whole-carcass rinses were examined for aerobic plate count (APC) on tryptic soy agar and coliforms on violet red bile agar. Untreated controls were also examined for Salmonella. In the laboratory study, lactic acid produced a significant (P < 0.01) Salmonella reduction compared with the inoculated no-rinse, water, and chlorine treatments, which were statistically similar to each other. In the field study, no Salmonella was detected on untreated controls. Lactic acid produced significant >2-log (P < 0.01) reductions in APC and coliforms, whereas chlorine resulted in slight, but significant 0.4-log reductions (P < 0.01) and 0.21-log reductions (P < 0.05) in APC and coliforms compared with untreated controls. Considering laboratory and field studies, lactic acid produced greater reductions in Salmonella, APC, and coliforms, validating its effectiveness as a chlorine alternative in mobile poultry slaughter operations.

Effect of Anaerobic Digestion and Application Method on the Presence and Survivability of E. coli and Fecal Coliforms in Dairy Waste Applied to Soil

Animal wastes are commonly used in a sustainable manner to fertilize crops. However, manures contain numerous pathogenic bacteria that can impact animal and human health. Treatment of animal waste by anaerobic digestion has the potential to reduce pathogen loading to land. This study was conducted to determine the fate of bacteria applied in raw and anaerobically digested dairy slurries that were broadcast and subsurface applied in a field of forage grasses. Digested slurry had significantly fewer indicator bacteria, Escherichia coli and fecal coliform at time of application. Anaerobic digestion did not increase the survivability of indicator bacteria. Waste treatment and application method did not affect the rate of bacteria die-off. There were fewer E. coli and fecal coliform at the end of each trial in the soils that received digested slurry. Anaerobic digestion of dairy waste has the potential to reduce pathogenic bacteria loading to cropland.

Influence of Seeding Ratio, Planting Date, and Termination Date on Rye-Hairy Vetch Cover Crop Mixture Performance under Organic Management

Cover crop benefits include nitrogen accumulation and retention, weed suppression, organic matter maintenance, and reduced erosion. Organic farmers need region-specific information on winter cover crop performance to effectively integrate cover crops into their crop rotations. Our research objective was to compare cover crop seeding mixtures, planting dates, and termination dates on performance of rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) monocultures and mixtures in the maritime Pacific Northwest USA. The study included four seed mixtures (100% hairy vetch, 25% rye-75% hairy vetch, 50% rye-50% hairy vetch, and 100% rye by seed weight), two planting dates, and two termination dates, using a split-split plot design with four replications over six years. Measurements included winter ground cover; stand composition; cover crop biomass, N concentration, and N uptake; and June soil NO3 --N. Rye planted in mid-September and terminated in late April averaged 5.1 Mg ha-1 biomass, whereas mixtures averaged 4.1 Mg ha-1 and hairy vetch 2.3 Mg ha-1. Delaying planting by 2.5 weeks reduced average winter ground cover by 65%, biomass by 50%, and cover crop N accumulation by 40%. Similar reductions in biomass and N accumulation occurred for late March termination, compared with late April termination. Mixtures had less annual biomass variability than rye. Mixtures accumulated 103 kg ha-1 N and had mean C:N ratio <17:1 when planted in mid-September and terminated in late April. June soil NO3 --N (0 to 30 cm depth) averaged 62 kg ha-1 for rye, 97 kg ha-1 for the mixtures, and 119 kg ha-1 for hairy vetch. Weeds comprised less of the mixtures biomass (20% weeds by weight at termination) compared with the monocultures (29%). Cover crop mixtures provided a balance between biomass accumulation and N concentration, more consistent biomass over the six-year study, and were more effective at reducing winter weeds compared with monocultures.