Solid Beef Cattle Manure Research Articles

Manure Application Timing and Tillage Influence on Nutrient Loss from Snowmelt Runoff

Winter manure application contributes substantial nutrient loss during snowmelt and influences water quality. The goal of this study is to develop best management practices (BMPs) for winter manure management. We compared nutrient concentrations in snowmelt runoff from three dates of feedlot solid beef manure application (November, January, and March) at 18 tons ha−1 on untilled and fall-tilled plots. The manure was applied at a single rate. Sixteen 4 m2 steel frames were installed in the fall to define individual plots. Treatments were randomly assigned so that each tillage area had two control plots, two that received manure during November, two in January, and two in March. Snowmelt runoff from each individual plot was collected in March and analyzed for runoff volume (RO), ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total dissolved phosphorus (TDP). Snowmelt runoff concentrations and loads of NH4-N, TKN, TP, and TDP were significantly higher in runoff from manure application treatments compared to control. The concentration of NH4-N and loads of NH4-N and TDP were significantly (p = 0.05) greater (42%, 51%, and 47%, respectively) from untilled compared to fall-tilled plots. The November application significantly increased RO, NH4-N, and TDP concentrations and loads in the snowmelt runoff compared to January and March applications. Results showed that nutrient losses in snowmelt runoff were reduced from manure applications on snow compared to non-snow applications. The fall tillage before winter manure application decreased nutrient losses compared to untilled fields.

Ammonia emission from manures treated with different rates of urease and nitrification inhibitors

Urease inhibitors have been successfully used to reduce ammonia (NH3) emission from urea-based fertilizers. However, studies on its effectiveness with manures have produced inconclusive results. Field and greenhouse studies were conducted to investigate the effectiveness of different rates of urease [N-(n-butyl) thiophosphoric triamide; NBPT] with and without nitrification inhibitor (NI) in reducing NH3 emission from surface-applied liquid pig manure (LPM) and solid beef manure (SBM). Ammonia emission was measured with acid-charged discs at seven dates for 28 d. Total NH3 emission (% of applied N) ranged from 4.3% to 8.2% in untreated LPM and 8.2% in untreated SBM. The corresponding NH3 emission was 6.8%–7.4% in LPM treated with NBPT, 5.0%–12.3% in LPM treated with NBPT + NI (double inhibitor; DI), and 6.0%–10.8% in SBM treated with DI. In the field study, NH3 emission was not significantly different between either LPM or SBM treated with and without DI. In the greenhouse, NBPT did not significantly reduce NH3 emission from LPM, whereas DI applied at a lower rate significantly increased NH3 emission from LPM. In conclusion, addition of NBPT to manure did not have any significant environmental benefit, whereas a combination of NBPT and NI increased NH3 emission from manure.

Aerial Nitrogen Fluxes and Soil Nitrate in response to Fall-Applied Manure and Fertilizer Applications in Eastern South Dakota

Manure and inorganic fertilizer help to meet crop nitrogen demand by supplementing soil nitrogen (N). However, excessive N losses reduce soil fertility and crop yield and can impair water and air quality. The objectives of the research were to compare different forms of fall-applied N for (1) the change in soil nitrate (NO3-N) over the growing season and (2) the aerial ammonia (NH3) and nitrous oxide (N2O) fluxes during the fall and early growing season. Treatments included solid beef cattle manure with bedding (BM), solid beef cattle manure only (SM), urea (UO), and no fertilizer (NF). The two-year plot-scale study took place in Brookings County, South Dakota, under rain-fed conditions in a silty clay loam. Manure and urea were applied at equal plant-available N rates of 130 and 184 kg·N·ha−1in Y1 and Y2, respectively, according to the South Dakota nutrient management planning process. The average total (i.e., 0–0.60 m soil depth) soil NO3-N for Y1 (83 kg·ha−1) was significantly higher than Y2 (67 kg·ha−1), whereas surface (i.e., 0–0.15 m soil depth) soil NO3-N was not significantly different between years. The average surface soil NO3-N (33.5 kg·ha−1) and total soil NO3-N (105.0 kg·ha−1) for UO were significantly higher than the remaining treatments (P<0.05). Soil water NO3-N concentrations, leaf-N, corn-grain-N, and yield measurements did not indicate any significant differences between treatments. Based on the two-year average, the highest NH3-N flux occurred from the BM (3.4 g·ha−1·h−1); however, this flux was only significantly higher than NF (1.4 g·ha−1·h−1). The NH3-N fluxes from UO (2.2 g·ha−1·h−1) and SM (1.7 g·ha−1·h−1) were similar to both BM and NF. The N2O-N flux from UO (0.79 g·ha−1·h−1) was significantly greater than NF (0.25 g·ha−1·h−1), while BM- (0.49 g·ha−1·h−1) and SM-produced (0.33 g·ha−1·h−1) N2O-N fluxes were not significantly different than neither UO nor NF. The three fall-applied N sources had similar aerial-N fluxes even though urea application resulted in significantly higher soil nitrate.

Beef Manure and Urea Applied to Corn Show Variable Effects on Nitrous Oxide, Methane, Carbon Dioxide, and Ammonia

Land application of beef cattle (Bos taurus) manure can improve soil health and increase corn (Zea mays L.) yield compared with commercial fertilizers. However, ammonia (NH₃), nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) emissions may lead to nutrient losses and environmental concerns. The objective of this research was to quantify NH₃, N₂O, CO₂, and CH₄ emissions from commercial and manure fertilizers applied to corn. In addition, residual soil N, corn yield, plant tissue N, and grain N were determined. The 2-yr field study was conducted in Fargo-Ryan silty clay soil. Treatments consisted of urea only (UO), solid beef manure (SM), solid beef manure with straw bedding (BM), and no fertilizer (NF). All treatments were applied to meet the corn N demand and yield goal of 10,760 kg ha–¹ (160 bu ac–¹). Greenhouse gases were quantified using static flux chambers, and NH₃ was quantified using acid traps, for a total of 13 measurement dates in each growing season. Manure applied to soil reduced cumulative N₂O by 23% in SM and 31% in BM compared with the UO soil. Cumulative CO₂ emission (cCO₂) was 42% lower in UO than in SM or BM. Cumulative CH₄ emission (cCH₄) ranged from –0.04 (NF) to 0.21 (BM) kg CH₄–C ha–¹, with the highest emission from BM. Cumulative NH₃ emission (cNH₃) was 11% lower in manure than UO. Cumulative residual soil N was 11% greater in Year 2. Fertilizer source did not affect the yield and grain N uptake (P > 0.05). The results highlight the challenges that come with variability in manure, soil, and weather as well as the potential for meeting crop N demand while reducing greenhouse gas emissions when using manure as an N source.

Temperature response of ammonia and greenhouse gas emission from manure amended silty clay soil

ABSTRACTSoil temperature plays an important role in organic matter decomposition, thus likely to affect ammonia and gaseous emission from land application of manure. An incubation experiment was conducted to quantify ammonia and greenhouse gas (GHG) (N2O, CO2 and CH4) emissions from manure and urea applied at 215 kg N ha−1 to Fargo-Ryan silty clay soil. Soil (250 g) amended with solid beef manure (SM), straw-bedded solid beef manure (BM), urea only (UO), and control (CT) were incubated at 5, 10, 15, and 25 °C for 31 days at constant 60% water holding capacity (WHC). The cumulative GHGs and NH3 emission generally increased with temperature and highest emission observed at 25 °C. Across temperature levels, 0.11–1.3% and 0.1–0.7% of the total N was lost as N2O and NH3, respectively. Cumulative CO2 emission from manure was higher than UO and CT at all temperatures (P < 0.05). Methane accounted for <0.1% of the total C (CO2 + CH4) emission across temperatures. The Q10 values (temperature sensitivity coefficient) derived from Arrhenius and exponential models ranged 1.5–3.7 for N2O, 1.4–6.4 for CO2, 1.6–5.8 for CH4, and 1.4–5.0 for NH3. Our results demonstrated that temperature significantly influences NH3 and GHG emissions irrespective of soil amendment but the magnitude of emission varied with soil nutrient availability and substrate quality. Overall, the highest temperature resulted in the highest emission of NH3 and GHGs.

Release of Ammonia and Greenhouse Gases along Moisture Gradient from Manure and Urea Applied Fargo Silty Clay Soil

Abstract. Greenhouse gas (GHG) [nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4)] emission and ammonia (NH3) volatilization from organic and commercial fertilizers are likely related to soil moisture levels. Effect of soil moisture [(30%, 60%, and 90% water-holding capacity (WHC)] on emissions from urea and manure treated (215 kg ha-1) Fargo-Ryan silty clay soil was studied under laboratory conditions. Soils (250 g) amended with solid beef manure (SM), straw-bedded solid beef manure (BM), urea (UR), and control (CT) were incubated for 28 days at 22±1°C, to determine GHGs (N2O, CO2, and CH4) emission and NH3 volatilization loss. The cumulative emission of N2O-N, CO2-C, and CH4-C ranged from 27 to 4402 µg N2O-N kg-1, 272 to 2030 mg CO2-C kg-1, and 10.1 to 1389 µg CH4-C kg-1 soil, respectively. The daily fluxes and cumulative emissions of N2O and CO2 generally followed the decreasing order of 30% &amp;lt; 90% &amp;lt; 60% of WHC. At 60% WHC, 1.01% of the total applied N was lost as N2O from urea treated soil. Carbon dioxide emission from manure treated soil (SM and BM) was up to two times the emission from UR treated soils. The Fargo clay soils showed higher CH4 emission at 90% WHC level. The cumulative NH3 volatilization loss from soil ranged from 29.4 to 1250.5 µg NH3-N kg-1, with the highest loss from UR amended soils at 30% WHC. These results suggest that gaseous emissions from manure and urea application under laboratory study are influenced by moisture levels of Fargo-Ryan silty clay soil. Keywords: Beef manure, Greenhouse gas, Soil water, Urea, Water holding capacity.

Nitrous Oxide Emitted from Soil Receiving Anaerobically Digested Solid Cattle Manure

Limited information is available about soil nitrous oxide (NO) fluxes, NO emission factors (EFs), and yield-scaled NO emissions for biogas residues used to fertilize crops in semiarid regions. To address this knowledge gap, a 4-yr field experiment was conducted in a semiarid climate to determine growing season NO fluxes from soil receiving (i) anaerobically digested solid beef cattle manure (digestate), (ii) separated solids from the digestate (separated solids), and (iii) undigested solid beef cattle manure (cattle manure) applied to target one and two times the recommended rates (200 and 400 kg total N ha) for barley ( L.) forage, assuming 50% of N was annually plant available. Nitrous oxide fluxes were determined using vented static chambers. Over the four growing seasons, 95, 80, and 81% of the NO flux occurred within 36 d of applying digestate, separated solids, and cattle manure, respectively. The cumulative NO emissions with digestate were 4.7 and 4.1 times the values of the separated solids and cattle manure, respectively. The digestate NO EF was 13.6 and 10.6 times the values of the separated solids and cattle manure, respectively, but the NO EF based on applied mineral N was similar for all amendments. The yield-scaled NO emissions with digestate were 4.3 and 3.6 times the values of the separated solids and cattle manure, respectively. In the semiarid region of southern Alberta, liquid biogas residues have a higher risk for NO emissions than both the separated solid fraction of the biogas residues and undigested cattle manure.

Anaerobically Digested Cattle Manure Supplied More Nitrogen with Less Phosphorus Accumulation than Undigested Manure

Core Ideas Barley recovered 19% of N applied by anaerobically digested cattle manure over 4 yr. Barley recovered 10% of N applied by undigested cattle manure over 4 yr. Separated solids and cattle manure supplied similar amounts of N and P to barley. Pelletized separated solids released N too slowly for a barley yield benefit. Separated solids posed a greater risk of P accumulation than cattle manure. Solid beef cattle manure is a good anaerobic digestion feedstock for methane production, but more research is needed to determine how co‐products of the anaerobically digested manure may be used in crop production, while limiting the risk of nutrient loss to the environment. Over four growing seasons, we measured the N and P supplied to barley (Hordeum vulgare L.) forage test crops from (i) anaerobically digested solid beef cattle manure (digestate), (ii) separated solids from the digestate (separated solids), (iii) pelletized separated solids (pellets), and (iv) undigested solid beef cattle manure (manure) that were applied to target 1× (260 kg N ha−1) and 2× (520 kg N ha−1) the recommended N rates. Non‐amended soil was the control. Digestate led to 31 to 50% greater barley forage yield than the other amendments. The apparent N recovery from digestate (19%) was much greater than pellets (2%) and about double that of the separated solids (9%) and cattle manure (10%). The barley N uptake derived from digestate was 41%, which was significantly greater than manure (22%), separated solids (17%), and pellets (2%). Digestate increased P uptake, while significantly reducing soil‐test P accumulation compared with the other co‐products and cattle manure when applied at N‐based rates. Our results confirmed that management practices for solid beef cattle feedlot manure may be used for separated solids, but not digestate. Pelletized separated solids may be an effective slow release fertilizer, while also supplying C, but determination of its nutrient release patterns is required.

Effect of beef cattle manure application rate on CH4 and CO2 emissions

In a series of field experiments, emissions of two major greenhouse gases (GHGs), methane (CH4) and carbon dioxide (CO2) were measured using a closed chamber technique in summer 2010 to evaluate the effects of solid beef cattle manure land application techniques. The treatments included a control (C: no manure), two manure application rates (40 and 80 T ha−1), and two injection layers (surface vs. subsurface (5 cm)): (1) 40 T ha−1 on surface (S40), (2) 80 T ha−1 on surface (S80), (3) 40 T ha−1 at subsurface (D40), and (4) 80 T ha−1 at subsurface (D80)). The exchange patterns of CH4 and CO2 in the control were variable and showed both emission and deposition. However, only emissions were seen in the manure treatments. Emissions of CH4 were seen systematically on the ascending order of 5.35 (C), 59.3 (S40), 68.7 (D40), 188 (S80), and 208 μg m−2 h−1 (D80), while those of CO2 also showed a similar trend: 12.9 (C), 37.6 (S40), 55.8 (D40), 82.4 (S80), and 95.4 mg m−2 h−1 (D80). The overall results of our study suggest that the emissions of CH4 and CO2 are affected most noticeably by the differences in the amount of manure application.

Solid beef cattle manure application impacts on soil properties and 17β-estradiol fate in a clay loam soil

Livestock manure applied to agricultural land is one of the ways natural steroid estrogens enter soils. To examine the impact of long-term solid beef cattle (Bos Taurus) manure on soil properties and 17β-estradiol sorption and mineralization, this study utilized a soil that had received beef cattle manure over 35 years. The 17β-estradiol was strongly sorbed and sorption significantly increased (P < 0.05) with increasing soil organic carbon content (SOC) and with an increasing annual rate of beef cattle manure. The 17β-estradiol mineralization half-life was significantly negatively correlated, and the total amount of 17β-estradiol mineralized at 90 days (MAX) was significantly positively correlated with 17β-estradiol sorption. The long-term rate of manure application had no significant effect on MAX, but the addition of fresh beef cattle manure in the laboratory resulted in significantly (P < 0.05) smaller MAX values. None of the treatments showed MAX values exceeding one-third of the 17β-estradiol applied.

Nutrients and sediment in frozen-ground runoff from no-till fields receiving liquid-dairy and solid-beef manures

Nutrients and sediment in surface runoff from frozen agricultural fields were monitored within three small (16.0 ha [39.5 ac] or less), adjacent basins at a no-till farm in southwest Wisconsin during four winters from 2003 to 2004 through 2006 to 2007. Runoff depths and flow-weighted constituent concentrations were compared to determine the impacts of surface-applied liquid-dairy or solid-beef manure to frozen and/or snow-covered ground. Despite varying the manure type and the rate and timing of applications, runoff depths were not significantly different among basins within each winter period. Sediment losses were low (generally less than 22 kg ha⁻¹ [20 lb ac⁻¹] in any year) and any statistical differences in sediment concentrations among basins were not related to the presence or absence of manure or the amount of runoff. Concentrations and losses of total nitrogen and total phosphorus were significantly increased in basins that had either manure type applied less than one week preceding runoff. These increases occurred despite relatively low application rates. Lower concentrations and losses were measured in basins that had manure applied in fall and early winter and an extended period of time (months) had elapsed before the first runoff event. The highest mean, flow-weighted concentrations of total nitrogen (31.8 mg L⁻¹) and total phosphorus (10.9 mg L⁻¹) occurred in winter 2003 to 2004, when liquid-dairy manure was applied less than one week before runoff. On average, dissolved phosphorus accounted for over 80% of all phosphorus measured in runoff during frozen-ground periods. The data collected as part of this study add to the limited information on the quantity and quality of frozen-ground runoff at field edges, and the results highlight the importance of manure management decisions during frozen-ground periods to minimize nutrients lost in surface runoff.

Phosphorus Losses in Simulated Rainfall Runoff from Manured Soils of Alberta

Manure applied to agricultural land at rates that exceed annual crop nutrient requirements can be a source of phosphorus in runoff. Manure incorporation is often recommended to reduce phosphorus losses in runoff. A small plot rainfall simulation study was conducted at three sites in Alberta to evaluate the effects of manure rate and incorporation on phosphorus losses. Treatments consisted of three solid beef cattle manure application rates (50, 100, and 200 kg ha(-1) total phosphorus), an unmanured control, and two incorporation methods (nonincorporated and incorporated with one pass of a double disk). Simulated rain was applied to soils with freshly applied and residual (1 yr after application) manure at 70 mm h(-1) to produce 30 min of runoff. Soil test phosphorus (STP), total phosphorus (TP), and dissolved reactive phosphorus (DRP) concentrations in runoff increased with manure rate for fresh and residual manure. Initial abstraction and runoff volumes did not change with manure rate. Initial abstraction, runoff volumes, and phosphorus concentrations did not change with manure incorporation at Lacombe and Wilson, but initial abstraction volumes increased and runoff volumes and phosphorus concentrations decreased with incorporation of fresh manure at Beaverlodge. Phosphorus losses in runoff were directly related to phosphorus additions. Extraction coefficients (slopes of the regression lines) for the linear relationships between residual manure STP and phosphorus in runoff were 0.007 to 0.015 for runoff TP and 0.006 to 0.013 for runoff DRP. While incorporation of manure with a double disk had no significant effect on phosphorus losses in runoff from manure-amended soils 1 yr after application, incorporation of manure is still recommended to control nitrogen losses, improve crop nutrient uptake, and potentially reduce odor concerns.

Culturable Escherichia coli in Soil Mixed with Two Types of Manure

We evaluated the impact of the manure type used in soil–manure mixtures on the detection of culturable E. coli as tested in water quality monitoring. A series of incubation experiments, lasting up to 200 d, allowed evaluation of the potential impact of manure × soil interactions on the augmentation of culturable E. coli Two soil types (sandy loam and a silt loam), two manure types (liquid swine manure and solid beef cattle manure), and three temperature levels (4, 12, and 20°C) were investigated. The significance of the presence of competing microorganisms was estimated by comparing results from manure mixtures with sterile and nonsterile soils. Water content in the soil–manure mixtures was maintained close to field capacity to eliminate the specific impact of water availability. We found that culturability of the indicator organism, E. coli, changed with time and was dependent on the type of manure used and its interaction with soil. Escherichia coli could be cultured for a longer time from soils with liquid manure additions. Whereas E. coli numbers were initially higher from soils treated with solid beef cattle manure, their numbers decreased more rapidly and the duration of their apparent survival was shorter. Resilience of culturable E. coli was independent of their initial numbers in manure.

Short-term nitrogen dynamics in soil amended with fresh and composted cattle manures

The amount of available nitrogen in fresh and composted manures is required to adjust inorganic fertilizer applications for crops when using manures and composts. Corn (Zea mays L.) plants were grown for 8 wk at temperatures of 17–27 °C and 12–18 °C in soil amended with two rates of fresh and composted solid beef cattle manure. Apparent N uptake of corn grown in soil amended with fresh solid beef cattle manure, composted beef cattle manure and (NH4)2SO4 at the higher temperature was 2, 8, and 36%, respectively, during this 8-wk period. Nitrogen uptake by corn in fresh solid beef cattle manure-amended soil at low temperature was affected by factors other than N availability. A 12-wk laboratory experiment was performed in which 15NH4+ was added to fresh and composted manure-amended soil to determine the fate of the inorganic N in the manure and to measure N mineralization rates. Net immobilization of inorganic N occurred with all manures; however, after 3 wk, net mineralization occurred with the solid and composted beef cattle manure. Immobilization of 15N continued with all manure amendments as a result of mineralization-immobilization turnover. The amount of unrecovered 15N after 12 wk was 10.5, 2 and 1% of the added 15N in soil amended with solid beef cattle manure, composted beef cattle manure and manure composted with bark, respectively. Key words: Composted manure, nitrogen availability, 15N, immobilization, remineralization, temperature

Nitrogen availability for corn in soils amended with urea, cattle slurry, and solid and composted manures

This study was conducted to determine whether manure N availability for corn (Zea mays L.) was best estimated by a component of the manure N or by soil inorganic N in May or June. Liquid dairy cattle manure, solid beef cattle manure, and composted beef cattle manure were applied in the spring of 1988, 1989 and 1990 at rates of 100, 200 and 300 kg N ha−1. Urea was applied at rates of 50, 100 and 150 kg N ha−1 for comparison. The N recovery by the harvested portion of the corn (grain + stover) in 1988 and 1990 averaged 49, 18, and 5% of the total N in urea, liquid dairy cattle manure, and solid or composted beef cattle manure, respectively. There was no yield response to any N source in 1989 because of high soil fertility. Relative nitrogen uptake by the corn grain + stover in 1988 and 1990 was significantly correlated with inorganic N applied as manure or fertilizer (r2 = 0.56), but not with total N applied (r2 = 0.02). When the data from all 3 years were analyzed, relative nitrogen uptake was better correlated with soil NH4 + NO3 in mid-May and soil NO3 in early-June (r2 = 0.83 and 0.76, respectively), than with inorganic N applied as manure or fertilizer (r2 = 0.20). A soil N test after manure application in mid-May to early June may be the best N management tool for corn production on livestock farms in Ontario. Key words: Animal manure, fertilizer, corn yields, soil nitrate test, nitrogen availability

EFFETS À LONG TERME D’APPORTS DE FUMIER SOLIDE DE BOVINS SUR L’ÉVOLUTION DES CARACTERISTIQUES CHIMIQUES DU SOL ET DE LA PRODUCTION DE MAIS-ENSILAGE

A long-term field experiment was initiated on a Neubois silty loam in 1978 in the county of Levis, Québec to study the changes in soil characteristics and silage corn yields following manure application. Solid beef cattle manure was incorporated without fertilizer every 2 yr in fall, at rates of 0, 20, 40, 60, 80 and 100 t ha−1. Even when significant differences were observed between treatments low corn yields were obtained from 1978 to 1984. These low yields were related to the low N, P and K recoveries from applied manure. For the 20 t ha−1 application rate, N. P and K recoveries from manure in the first year were 28, 7 and 1396, respectively. N, P and K recovery decreased with manure application rates. Corn yields increased progressively, but they achieved their maximum value (10–12 t ha−1 DM) only in 1985 and after three manure applications. This was due to the important residual effect of manure. Highly significant increases in N (7–64%), P (80–300%) and K (37–158%) as well as other nutrients were associated with manure applications. Manure application also significantly increased soil pH, CEC and organic matter. Average yearly increases of organic matter content were 0.06% and 0.16% for 20 to 40 t ha−1, respectively, and varied from 0.20 to 0.30% for the highest application rates (60–100 t ha−1). These improvements of soil properties constitute the "indirect effect" of manure. This study showed that percent recovery of N, P and K from solid cattle manure was generally low. Thus, manure should be mainly considered as an organic amendment.Key words: Solid cattle manure, corn silage, percent recovery, pH, mineral nutrients, cation exchange capacity, organic matter

CORN RESPONSE TO RESIDUAL N FROM UREA AND MANURES APPLIED IN PREVIOUS YEARS

The response of corn (Zea mays L.) to residual N from several manures and urea was determined in the first and second years following application. Grain yields were obtained from six field trials conducted over a 12-yr period at the Elora Research Station. Manures or urea were applied at several rates during 1 or more years followed by 2 yr (3 yr for one trial) of yield measurements when N treatments were not applied. During the years when corn grain yield response to residual N was determined, one-half of each plot received 120 kg N ha−1 as anhydrous ammonia. This provided a potential yield which was used to evaluate a residual "organic manure" effect or the effect of manure in increasing yields over those obtained only with chemical fertilizers including N. The results indicated that yield responses from residual N from liquid dairy cattle manure and solid beef manure were considerably lower than that from liquid poultry manure and urea in the first year. In the second year there was only a small response from residual N from any of the sources. These results were used to formulate a "decay series" which agreed generally with several published decay series in that response to residual N decreased in a curvilinear manner. Residual N appeared to be less available than predicted by published decay series especially after the second year. There was no clear evidence in this study that manures provided an additional "organic manuring" effect of increasing yields over those obtained only with chemical fertilizers. Key words: Residual manure N, organic manuring effects, decay series

AVAILABILITY OF NITROGEN FROM THREE MANURES TO CORN IN THE FIELD

Three manures were compared with urea as sources of nitrogen for corn (Zea mays L.) on a different field site in each of 3 yr. The manures and their average [Formula: see text]–N:total N ratios were as follows: liquid poultry manure (LPM), 0.89; liquid dairy cattle manure (LCM), 0.53; and solid beef cattle manure (SBM), 0.09. The manures were applied at rates of 100, 200 and 300 kg total N ha−1. An additional LCM treatment of 600 kg total N ha−1 was also included. For comparison with the manures as N sources, urea was applied at rates of 50, 100 and 150 kg N ha−1. The yield response data were examined on the basis of a previously suggested model which predicted that all of the [Formula: see text]–N and part (e.g., 10–20%) of the organic N in manures are available for crop growth in the field. Regression analyses of paired yield data sets of urea and LCM or urea and LPM indicated that only 75–80% of the [Formula: see text]–N fraction applied in these manures was equivalent to urea-N. Thus, it was concluded that the model did not take into account net N immobilization and possibly N losses through denitrification following application. It was concluded also that N release from the organic N fraction of SBM differed substantially from that for the other manures. This conclusion was supported by greenhouse data which indicated that net N immobilization occurred for the first crop shortly after SBM was applied but this was followed by net N mineralization for a second crop as manure decomposition continued. Soil NO3− concentrations in mid-June generally increased with the urea, LPM and LCM sources of N at the higher rates of application in the field. Lower soil NO3− concentrations with SBM reflected the lower availability of N. Key words: Corn, manure N availability, Zea mays L.

Application of Cattle Waste on Sloping Cropland1,2

Effects of applying cattle manure to sloping cropland on runoff water quality, corn yield and composition, and soil chemical composition were evaluated in a 4-yr field study. Dairy cattle slurry (6 to 8% dry matter) at 25 and 105t/ha during yr 1 and 2 and solid beef manure (22 to 24% dry matter) at 49 and 52t/ha during yr 3 and 4 were surface-applied to .81 and 1.05ha watersheds with a 6% slope. Manure applications increased corn yields compared to the control, especially with the higher rates of dry matter application the last 2 yr of the study. Corn leaf nutrient concentrations tended to reflect changes in nutrient loading from manure applications. Soil nitrate nitrogen, exchangeable phosphorus, and exchangeable potassium tended to increase with manure application. Nutrient concentrations in runoff water were not elevated adversely by manure application. Mild winter weather during the study allowed for some adsorption of waste nutrients in the soil. With relatively mild winter weather, applying up to 105t/ha of liquid cattle slurry or 52t/ha of solid cattle waste annually to cropped land with a 6% slope did not present a significant pollutant problem.