Manure Application Treatments Research Articles

Long-term manuring enhances soil gross nitrogen mineralization and ammonium immobilization in subtropical area

Manure amendments have been generally considered to enhance soil nutrient supply, thus improving soil fertility and crop productivity, especially in subtropical area. However, the underlying mechanisms of manure application effects on soil nitrogen (N) supply capacity and N transformation processes remain uncertain. Here, 15N isotope pool dilution techniques were used to determine the gross rates of N mineralization, ammonium (NH4+) immobilization and nitrification in red soil subjected to three decades of long-term fertilization regimes. Results showed that compared to treatments without manure, manure application alone or combined with chemical fertilizers significantly increased gross N mineralization rates by 4.55−8.31 folds, resulting from increased N-acquiring enzyme activity and decreased microbial N use efficiency (NUE). The decreased microbial NUE in the manure application treatments was due to alleviated imbalance of C:N between soil and microbial biomass. Gross NH4+ immobilization rates were 7.35−11.34 folds higher in the treatments amended with manure (1.51−2.23 mg N kg−1 d−1) relative to without manure, attributed to increased microbial biomass and bacterial abundance. Compared to chemical fertilizers application, manure application decreased gross nitrification rates by 38−55%, due to the decline in NH4+ availability via enhanced NH4+ immobilization. The significantly lower ratio of gross nitrification to NH4+ immobilization in the treatments with manure suggested that manure amendments could potentially mitigate the risk of soil N losses. Overall, long-term manuring has the potential to improve soil N supply and retention capacities by enhancing gross N mineralization and NH4+ immobilization accompanying with decreased gross nitrification.

Effect of Combined Application of Chicken Manure and Inorganic Nitrogen Fertilizer on Yield and Quality of Cherry Tomato

Unreasonable application of inorganic nitrogen (N) fertilizer on cherry tomatoes (Solanum lycopersicum var. cerasiforme) has resulted in serious environmental threats. The advantages of application of organic manure combined with inorganic N fertilizer for vegetable production systems have been reported widely, but there are still few studies on cherry tomato production. Therefore, this study aims to determine the impact of a combined application of organic manure (in form of chicken manure at different application rate of 0 and 40 t ha−1) with inorganic N fertilizer (in form of urea at various N application rates of 0, 160 and 320 kg N ha−1) on the fruit yield and quality of cherry tomato across two seasons. Results showed that inorganic N application exhibited positive effects on fruit yield and its associated components of cherry tomato. However, there was no significant difference in terms of fruit yield and its associated components between the two N rates of inorganic N (160 and 320 kg N ha−1), indicating that fruit yield is not improved significantly when the N application rate exceeds some threshold. Under chicken manure application treatments, however, an increased N rate did not show a positive effect on fruit yield. Importantly, chicken manure application has greatly increased fruit yield and fruit quality (represented by membership function indicator) by 43% and 23%, respectively in comparison with zero manure application. In particular, the soluble protein and titratable acid were increased by 124% and 118%, respectively. Overall, these results suggested that chemical N fertilizers could be largely replaced with chicken manure. Furthermore, the combined application of organic with inorganic N fertilizers seems to be a promising management practice for reducing the reliance on use of inorganic N fertilizer, while mitigating the environmental burden for cherry tomato production.

Dynamics of organic carbon and nitrogen in deep soil profile and crop yields under long-term fertilization in wheat-maize cropping system

Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity. The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization in the wheat-maize cropping system. Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure). Crop yield and the properties of topsoil were measured yearly from 2001 to 2009. C and N contents were measured at five different depths in 2001 and 2009. The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments. The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize. Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions. In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC. All fractions were higher under the manure application treatments than under the inorganic fertilization treatments. Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm). This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments. The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.

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.

Winter Annual Rye Seeding Date Influence on Nitrogen Recovery and Ammonia Volatilization from Late Fall Surface-Applied Manure

Dairy farmers in the northeast face challenges in the application of manure in fall and on-time planting of cool-season grasses to maximize recovery of residual N and nutrients released from fall applied manure. Ammonia emission from animal manure is a serious environmental concern and can be reduced if cover crop is integrated in the farming system. On-time planting of cover crops can reduce ammonia volatilization from fall, surface-applied manure, and prevents N loss to leaching. A two-year study was conducted in 2015 and 2016 to investigate if time of planting of winter annual rye (Secale cereale L.) along with late fall application of manure when air temperature is low can influence ammonia emission and preserve nitrogen (N) to meet the N requirement of forage rape. Three planting dates (16 September, 30 September, and 14 October) of rye cover crop with two manure application treatments including late-fall application and no manure were assessed for mitigating ammonia volatilization, and also yield and recovery of N by forage rape (Brassica napus L.). The highest rates of ammonia volatilization were detected in the first 24 hours after manure spreading regardless of the treatment. The result indicated that cover crop use significantly limited volatilization compared with no cover crop. The earliest planting date produced 3823 kg ha−1 dry matter of winter rye cover crop that was 16 and 35 percent higher than second and third dates of planting, respectively. The manured cover crop accumulated 132 kg N ha−1 when planted early. However, biomass yield of forage rape was more when planted after all cover crop treatments with manure application. Prior to forage planting, the nitrate-N content in all three soil depths (0–20, 20–40, and 40–60 cm) in the plots with manure was higher than plots with no manure. No significant differences in forage rape yield was detected among winter rye planting dates; however, forage rape planted after winter rye was higher than after no-cover crop. The results of this study suggest that when immediate incorporation of manure into soil is not feasible, establishing cover crop early and then applying manure in the late fall, is a practical management to limit nonpoint source pollution from ammonia loss.

Tree-scale spatial responses of extracellular enzyme activities and stoichiometry to different types of fertilization and cover crop in an apple orchard

The effects of cover crops and fertilization on the soil properties of apple orchards have been studied widely, but our knowledge of the variations in the soil enzyme activity and stoichiometry remains limited, particularly the tree-scale spatial responses. In this study, field experiments were conducted in two main plots comprising cover crop (CC) and no cover crop (NC) treatments with four sub-plots comprising no fertilization, manure (M), N, P, and K fertilizer (NPK), and NPK fertilizer combined with manure (NPKM). We determined the activities of C, N, and P acquisition enzymes comprising β-1,4-glucosidase, (BG), β-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and alkaline phosphatase (PHOS), the soil nutrient contents, and microbial biomass. Cover crop and fertilization significantly affected the soil nutrient contents, microbial biomass, and enzyme activities. Cover crop growth decreased the BG:NAG + LAP and BG:PHOS enzyme activity ratios (before mowing and mulching the cover crop). Fertilization also influenced the BG:NAG + LAP, BG:PHOS, and NAG + LAP:PHOS ratios. The soil enzyme activities were affected by the soil nutrient contents and microbial biomass, especially at distances 90 and 120 cm from the trees, as well as by the manure application treatments (M and NPKM). The soil enzyme ratios and microbial biomass ratio were influenced by the soil properties, especially at distances of 90 and 120 cm form the trees. The relationships among the soil properties, microbial biomass ratio, and soil enzyme ratios were affected by the growth of the cover crop and apple trees. The chemical fertilizer treatments (NPK and NPKM) significantly increased the negative relationships between the soil nutrient ratios and enzyme ratios. Our findings demonstrate that the C:N:P stoichiometry of the soil microbes and enzyme activities were affected by the cover crop and fertilization, and the spatial effects were detected at the tree-scale in an apple orchard.

The effect of 34-year continuous fertilization on the SOC physical fractions and its chemical composition in a Vertisol

Reports regarding the effects of long-term organic and inorganic fertilization on the quantity and quality of soil organic carbon (SOC), particularly in Vertisols, are scarce. In this study, we combined SOC physical fractionation with 13C NMR spectroscopy technology to investigate the effect of 34 years of continuous fertilization on the SOC physical fractions and its chemical composition of 0–20 cm soil layer in a Vertisol. This study consisted of six treatments: no fertilization (control), chemical nitrogen, phosphorus and potassium fertilizers (NPK), low and high amounts of straw with chemical fertilizers (NPKLS and NPKHS), and pig or cattle manure with chemical fertilizers (NPKPM and NPKCM). Over 34 years of continuous fertilization, the SOC sequestration rate was from 0.08 Mg C ha−1 yr−1 in the control treatment to 0.66 Mg C ha−1 yr−1 in the NPKCM treatment, which was linearly related with the C input (P < 0.01). Of the five SOC physical fractions, two silt plus clay fractions (S + C_M, S + C_mM) dominated 74–92% of SOC, while three POM fractions (cPOM fPOM and iPOM) were only 8–26%. The two manure application treatments significantly increased all the SOC physical fractions except for the silt plus clay fraction within macroaggregates (S + C_M) compared with NPK treatment (P < 0.05), which was dependent on the larger amount of C input. Also, the two manure application treatments increased the levels of alkyl C and aromatic C but decreased O-alkyl C (P < 0.05), whereas the straw application (NPKLS and NPKHS) had no impact on the C functional groups (P > 0.05). Overall, the combination of animal manure with inorganic fertilization could enhance the SOC sequestration and alter its quantity and quality in Vertisols.

Effect of Cover Crop Species and Liquid Manure Application Rate on Green Manure Production, Leaf Mineral Content, Fruit Quality and Soil Chemical Properties in Pear Orchard

Cover cropping and liquid manure application are considered as effective ways to replace the use of chemical fertilizer in orchard. This study was conducted to investigate the effect of cover crop species and liquid manure application rate on green manure production, leaf mineral content, fruit quality and soil chemical properties in pear orchard. The treatments include rye and hairy vetch as cover crops, two liquid manure application levels based on N and <TEX>$K_2O$</TEX> requirement on each cover crop species, and chemical fertilizer as control. Green manure production was higher in hairy vetch than in rye. K content of pear leaves and soil exchangeable K content increased in N based liquid manure application treatments. The yield was higher in rye + liquid manure and fertilizer treatments, and fruit quality was not different between the treatments. Taking all of these into account, rye + <TEX>$K_2O$</TEX> requirement-based liquid manure application is recommended in pear orchard for not only sufficient nutrient supply but also prevention of any problem related with soil <TEX>$K_2O$</TEX> accumulation in pear orchard in long-term perspective.

Surface soil quality in five midwestern cropland Conservation Effects Assessment Project watersheds

Soil quality (SQ) assessment is a proactive process for evaluating soil and crop management effects on biological, chemical, and physical indicators of soil health. Our objectives were to evaluate several SQ indicators within five Agricultural Research Service (ARS) experimental watersheds (WS) and determine if those indicators were affected by manure, tillage, or crop rotation histories. Ten soil quality indicators were measured within each of 600 0 to 5 cm (0 to 2 in) depth and 398 5 to 15 cm (2 to 6 in) depth increment samples, evaluated statistically, and then scored using the Soil Management Assessment Framework. Except for soil organic carbon (C) at both depth increments or microbial biomass C and β-glucosidase within the 5 to 15 cm increment, the indicators showed significant WS differences. Except for surface soil-test phosphorous (P), Soil Management Assessment Framework indicator scores and overall soil quality index values also showed significant (p ≤ 0.05) WS differences. Microbial biomass C was significantly affected by crop rotation at both sampling depths and by WS within the surface 5 cm. β-glucosidase was significantly affected by all four factors (WS, manure, tillage, and crop rotation) and their interactions within the 0 to 5 cm increment. The water-stable macroaggregate indictor within the 0 to 5 cm increment and within the 5 to 15 cm increment, however, were not significantly different for the tillage and manure application treatments, respectively. Our study showed that the ARS Conservation Effects Assessment Project (CEAP) watersheds provided a moderately controlled example that watershed-scale monitoring of soil quality is feasible and should be used to monitor soil health and/or conservation program effectiveness.

Maize–mucuna rotation: An alternative technology to improve water productivity in smallholder farming systems

Rain-fed crop production systems in the semi-arid tropics of Zimbabwe are characterized by low water productivity (WP), which is partly attributed to inherent low soil fertility, and further exacerbated by continuous cropping without addition of adequate organic and inorganic fertilizers due to unavailability and high costs. A simulation modeling approach was used to evaluate potential interventions that can be used as entry points to improve crop water productivity. Low-cost interventions that use locally available organic inputs were evaluated using the Agriculture Production Systems sIMulator (APSIM). The farmer practice (FP) was compared to interventions comprising manure application (MN) and maize–mucuna rotation (MMR). Their potential effects on crop water productivity, dynamics of soil organic carbon (SOC) and total nitrogen (TN) were assessed. Average maize grain water productivity was 0.32, 0.40 and 0.70kgm−3 under the FP, MN and MMR treatments, respectively, while that of mucuna biomass (Mucuna pruriens) was 1.34kgm−3. Cropping under the FP and MN treatments showed negative trends in SOC and TN over 30years, with average losses ranging from 17 to 74kgha−1yr−1 and 6 to 16kgha−1yr−1, respectively. In contrast, the MMR treatment showed positive trends in both soil organic carbon (SOC) and total nitrogen (TN). The SOC and TN increased by 2.6–194kgha−1yr−1 and 6–14kgha−1yr−1, respectively. According to the simulation results it can be concluded that the MMR treatment can improve the water productivity of smallholder maize systems in the semi-arid areas of Zimbabwe under nutrient-depleted soil conditions and can also contribute to the building up of SOC and TN.

Evaluation of ammonia emissions from manure incorporated with different soil aerator configurations

The incorporation of swine manure with tillage effectively reduces ammonia (NH₃) emissions and conserves crop available nitrogen (N) but is not compatible with no-till and many other conservation tillage programs. Rolling-tine aerators potentially provide a means to enhance manure infiltration with limited disruption of the soil surface; however, the impact of the range of aerator configurations and manure placements has not been widely studied. We measured NH₃ emissions, conducted presidedress nitrate (NO₃) tests (PSNT), monitored corn (<i>Zea mays</i> L.) grain yield when swine manure was incorporated with combinations of two aerator toolbar offset angles (0° and 10°) and two manure placements (broadcast before aeration and banded behind aerator), and compared those measurements to unincorporated surface application and an unmanured control. Additional plots were established with five rates of mineral N fertilization to determine N response curve and estimate fertilizer N equivalent of the applied manure. Measurement of cumulative NH₃ emissions using a dynamic chamber method showed that offsetting the aerator toolbar by 10° reduced emissions by 65% to 75%, with both manure placements, compared to surface application. However, no consistent reductions in NH₃ emissions were observed when the toolbar was not offset. While reduction in NH₃ with the offset toolbar could conserve substantial amounts of plant available N, the soil disturbance caused by the offset tines would not be compatible with most conservation tillage programs. Presidedress NO₃ test values increased when NH₃ emissions were reduced. In 2009, both the angled and straight aerator treatments with manure banded behind the aerator resulted in significantly higher corn grain yield than all other treatments despite reductions in NH₃ emissions only when the toolbar was angled. Correlation of yield from manure application treatments with the N response curve for multiple mineral N application rates showed a greater than expected response to manure application. Yield responses are an indication that aeration has benefits in addition to N conservation. We do not recommend the rolling-tine aerator if reducing NH₃ emissions in conservation tillage is the primary goal, but future study into other yield-increasing benefits of aeration is needed.

Uroda a technologicka kvalita ekologickej a low input produkcie zemiakov

The yield and other quantitative (number of plants, number of tubers, weight of tubers per 1 m2) and qualitative parameters (content of vitamin C, starch, nitrogen and dry matter) of the Solanum tuberosum L. early variety “Collete” have been studied in ecological and low-input farming systems with two levels of organic fertilization during 2003-2005. The experiment was situated in water-protected zone of western Slovakia on Luvi-Haplic Chernozem. After harvest of forecrop in higher level of organic fertilization treatment catch crop – phacelia and mustard was grown. Highly significant differences in each studied parameters of potato tubers between certain years were ascertained, thus great influence of weather conditions on quality and quantity of potatoes was confirmed. Yields was highly significantly influenced also by farming systems, when in low-input system the average yield was 21.38 t ha-1 and in ecological system 20.02 t ha-1. Green manure management did not influence yield significantly. In treatment without green manure the average yield 20.47 t ha-1 was reached with comparison to green manure application treatments 20.93 t ha-1. In low-input system significantly higher C vitamin content (4.23 mg 100g-1) was ascertained compared to ecological one 3.53 mg 100g-1. Other qualitative parameters were more or less on the same level. We recommended both farming system for growing potatoes in water vulnerable zones and for better fulfil the Good Agricultural Practices in Slovak conditions.

돈분액비 시용이 감자 생육, 토양화학성 및 침투수질에 미치는 영향

This study was carried out to determine the effects of pig slurry on growth of potato (Solanum tuberosum L. cv. Dejima), soil chemistry properties and infiltration water quality in volcanic ash soil and non-volcanic ash soil of Jeju. Fertilization of liquid pig manure was based on nitrogen. In volcanic ash soil and non-volcanic ash soil, there was no difference in the height and diameter of stems in chemical fertilizer and liquid pig manure application treatments. Also yields of potatoes were no significantly difference in chemical fertilizer and liquid pig manure application treatments. pH in all soil was increased by application of liquid pig manure compared to the chemical fertilizer plot. Contents of exchangeable K in all soil were accumulated excessively by fertilization of pig manure 100% compared to the chemical fertilizer 100%. But there was no difference between the chemical fertilizer 50%+liquid pig manure 50% and chemical fertilizer 100%. No difference between the chemical fertilizer and liquid pig manure was observed in available phosphate, exchangeable Ca and Mg. -N concentration of infiltration water sample collected at 70cm of soil depth was lower non-fertilizer than chemical fertilizer and liquid pig manure application treatments. In volcanic ash soil, the -N concentration of infiltration water was decreased from early, except liquid manure 100%. In non volcanic ash soil, the -N concentration of infiltration water increased until October 8, but then was reduced. In all soils, -N concentration of infiltration water was higher in the liquid manure 100% than those in the chemical fertilizer 100% and chemical fertilizer 50%+liquid pig manure 50%, but there were no differences. In conclusion, the growth of potato, fertilization of soil and -N content of infiltration water were not different between chemical 50%+liquid pig manure 50% and chemical 100% plot. So, liquid pig manure could be substituted for some amount of chemical fertilizer.

Soil organic C, nutrients, microbial biomass, and grain yield of rice (Oryza sativa L.) after 18 years of fertilizer application to an infertile paddy soil

We have studied the influence of long-term fertilization on organic C, nutrients, microbial biomass of soil, and grain yield of rice (Oryza sativa L.) after 18 years of inorganic and organic fertilizer application to an infertile paddy field under subtropical conditions. After 18 years of fertilization, soil organic C and total N contents were 9.56~12.17 and 1.01~1.25 g kg−1, which were 190~269% and 135~191% higher than those of the initial soil, respectively. Organic manure application increased soil organic C, total N, available N, and available P contents by 19.2%, 14.4%, 13.2%, and 78.3% on average compared with organic manure-omitted treatments. Phosphorus fertilizer application increased soil available P content more significantly than organic manure application, and it was an average 385% higher than P-omitted treatments. Soil microbial biomass C, N, and rice yield were 48.9%, 33.2%, and 133% higher in organic manure application treatments and 36.8%, 38.8%, and 239% higher in P fertilizer application treatments than organic manure-omitted or P-omitted treatments, respectively. Incorporation of organic manure-enhanced and P fertilizer-enhanced rice yields by 382% compared with the unfertilized treatment and yield increment index was 123% compared with that observed during 1991–1994, implying that organic manure application combined with P fertilizer was needed to ensure high and sustainable productivity. Rice yield was significantly correlated with all soil chemical properties except available K content, and stepwise regression analysis showed that soil available P content was the limiting factor to rice yield.

Root zone soil nitrogen management to maintain high tomato yields and minimum nitrogen losses to the environment

Greenhouse field experiments on tomato were carried out at Shouguang, Shandong province, over four double cropping seasons between 2004 and 2008 in order to understand the effects of manipulating root zone N management (RN) on fruit yields, N savings and N losses under conventional furrow irrigation. About 72% of the chemical N fertilizer used in conventional treatment (CN) inputs could be saved using the RN treatment without loss of yield. The cumulative fruit yields were significantly higher in the RN treatment than in the CN treatment. Average seasonal N from irrigation water (118 kg N ha −1), about 59% of shoot N uptake, was the main nitrogen source in treatments with organic manure application (MN) and without organic manure or nitrogen fertilizer (NN). N losses in the RN treatment were lowered by 54% compared with the CN treatment. Lower N losses were found in the MN and NN treatments due to excessive inputs of organic manure and fruit yields were consequently substantially affected in the NN treatment. The critical threshold of N min supply level in the root zone (0–30 cm) should be around 150 kg N ha −1 for sustainable production. April to May in the winter–spring season and September to October in the autumn–winter season are the critical periods for root zone N manipulation during crop growth. However, control of organic manure inputs is another key factor to further reduce surplus N in the future.

Evaluation of the PNM Model for Simulating Drain Flow Nitrate-N Concentration Under Manure-Fertilized Maize

Mathematical models may be used to develop management strategies that optimize the use of nutrients from complex sources such as manure in agriculture. The Precision Nitrogen Management (PNM) model is based on the LEACHN model and a maize N uptake/growth and yield model and focuses on developing more precise N management recommendations. The PNM model was evaluated for simulating drain flow nitrate-nitrogen (NO3-N) in a 3-yr study involving different times of liquid manure application on two soil textural extremes, a clay loam and a loamy sand under maize (Zea mays, L.) production. The model was calibrated for major N transformation rate constants including mineralization, nitrification and denitrification, and its performance was tested using two different calibration scenarios with increasing levels of generalization: (i) separate sets of rate constants for each individual soil type and (ii) a single set of rate constants for both soil types. When calibrated for each manure application treatment for each soil type, the model provided good simulations of monthly and seasonal drain flow NO3-N concentrations. The correlation coefficient (r) and Willmott’s index of agreement (d) ranged from 0.63 to 0.96 and 0.72 to 0.92, respectively. The calibrated model performed reasonably well when rate constant values averaged over manure application treatment for each soil type were used, with r and d values between 0.54 and 0.97, and 0.70 and 0.94, respectively, and greater accuracy for the clay loam soil. When rate constant values were averaged over manure application treatments and soil types, model performance was reasonably accurate for the fall time manure application on the clay loam (r and d of 0.60 and 0.91 and 0.72 and 0.92, respectively) and satisfactory for the spring time on the clay loam and the fall and spring times for the loamy sand soil (r and d between 0.56 and 0.90 and 0.58 and 0.84, respectively). The use of the model for predicting N dynamics under manure-fertilized maize cropping appears promising.