Corn and soybean grain yield responses to soil amendments and cover crop in upland soils

A field study was conducted on upland soils for six years to determine interactive effects of winter wheat (Triticum aestivum L.) cover crop, organic and inorganic soil amendments on grain yields and nutrient utilizations in a no-till corn (Zea mays)-soybean (Glycine max) rotation. Experimental design was a split-plot arrangement with four replicates. Cover crops were the main plots and fertilization treatments used as sub-plot. Fertilization treatments included an unfertilized control, poultry litter, poultry litter (PL) plus flue gas desulfurization (FGD) gypsum and inorganic N fertilizer applied every other year to corn. Corn grain yield and grain N and P uptake were greater with PL than inorganic fertilizer in 2014 and 2016. Addition of FGD gypsum to PL significantly increased corn grain yield by 15% in 2016. Cover crop increased corn and soybean grain yields in a year with less seasonal rainfall possibly by conserving soil moisture.     

Nitrous oxide emissions under a four-year crop rotation system in northern Japan: impacts of reduced tillage,composted cattle manure application and increased plant residue input

In the context of their role in global warming, nitrous oxide (N₂O) emissions from agricultural soil under different management practices were studied in Hokkaido, northern Japan. To assess the impacts of reduced tillage, composted cattle manure-based fertilization and amendments with crop residues and green manure on N₂O emissions from soil, a field experiment was conducted under a four-year crop rotation on a well-drained Andisol. The crop rotation included potato (Solanum tuberosum L.) or sweet corn (Zea mays L.), winter wheat (Triticum aestivum L.), sugar beet (Beta vulgaris L. subsp. vulgaris) and soybean (Glycine max (L.) Merr.). The cumulative N₂O emissions for the four-year study period differed widely (0.33 to 4.90?kg?N?ha^?1), depending on the treatments imposed, being the greatest for a combination of conventional moldboard plow tillage, composted cattle manure-based fertilization and increased plant residue input, and the lowest for a combination of conventional tillage, chemical fertilizer-based fertilization and normal plant residue input treatments. The cumulative N₂O emissions under reduced tillage were all small, irrespective of fertilization and plant residue input treatments. Composted cattle manure-based fertilization (P?≤?0.01) and increased plant residue input (P?≤?0.01) significantly increased cumulative N₂O emissions. Tillage showed a significant interaction with fertilization and plant residue input, indicating that N₂O emissions were enhanced when composted cattle manure, crop residues and green manure were incorporated by conventional tillage. In the present study, the N₂O emission factors for chemical fertilizer, composted cattle manure and crop residues were 0.26?±?0.44, 0.11?±?0.16 and ?0.03?±?0.52%, respectively, all much lower than the country-specific emission factor for Japan's well-drained soils (0.62%) and the default emission factor used in the IPCC guideline (1%).     

Maize productivity and soil carbon storage as influenced by wheat residue management

Wheat (Triticum aestivum L) residue removed, burnt, or incorporated with or without 0, 60, and 120 kg nitrogen (N) ha^?1 effects on maize (Zea mays L) hybrids (Pioneer-3025, Pioneer-30P45, and Kiramat) were assessed at University of Agriculture, Peshawar, Pakistan during 2010 and 2011 for maize production and soil carbon (C) storage. Pioneer-30P45 had higher grain yield, leaf area, and delayed maturity. Residue burning combined with 120 kg N ha^?1 produced higher grain yield. The leaf area, leaf area ratio, grain N content, and solar radiation interception were improved with N + residue burnt/incorporated over control. The grain yield was positively correlated with yield parameters. Soil organic carbon (SOC) content were in order of incorporated > burnt > removed at all growth stages (i.e., sowing, tasseling, maturity, and harvesting). Conclusively, wheat residue burnt/incorporated into the soil with 120 kg N ha^?1 was best for maize production of Pioneer-30P45; however residue incorporation into the soil improved SOC.     

Growth and reproduction of the vermicomposting earthwormPerionyx excavatus as influenced by food materials

An outdoor study was undertaken using polyethylene containers to assess the suitability of different organic residues, soybean straw (Glycine max L. Merril.), wheat straw (Triticum aestivum L.), maize stover (Zea mays L.), chickpea straw (citer arietinum L.) and city garbage, as food for the tropical epigeic earthwormPerionyx excavatus, and to assess the influence of this earthworm on the decomposition of these materials. Maize stover was found to be the most suitable of the food materials used. Population growth ofP. excavatus was enhanced by addition of these organic materials in the temperature range 24°-30°C, while the population was adversely affected above 30°C in a vermiculture system. Addition of earthworms accelerated the breakdown of residues, which ultimately resulted in a lowering of the C:N ratio, water-soluble carbon and carbohydrates, and increased ash percentage and cation exchange capacity compared with their respective controls.     

Sustaining Soil Quality with Legumes in No‐Tillage Systems

Abstract

Tillage, cropping system, and cover crops have seasonal and long‐term effects on the nitrogen (N) cycle and total soil organic carbon (C), which in turn affects soil quality. This study evaluated the effects of crop, cover crop, and tillage practices on inorganic N levels and total soil N, the timing of inorganic N release from hairy vetch and soybean, and the capacity for C sequestration. Cropping systems included continuous corn (Zea mays L.) and stalk residue, continuous corn and hairy vetch (Vicia villosa Roth), continuous soybeans (Glycine max L.) plus residue, and two corn/soybean rotations in corn alternate years with hairy vetch and ammonium nitrate (0, 85, and 170 kg N ha^?1). Subplot treatments were moldboard plow and no tillage. Legumes coupled with no tillage reduced the N fertilizer requirement of corn, increased plant‐available N, and augmented total soil C and N stores.     

Climatic Gradient,Cropping System,and Crop Residue Impacts on Carbon and Nitrogen Mineralization in No‐Till Soils

Abstract

In the West Central Great Plains of the United States, no‐till management has allowed for increased cropping intensity under dryland conditions. This, in turn, has affected the carbon (C) and nitrogen (N) mineralization dynamics of these systems. In this region, moisture stress increases from north to south due to an increase in evapotranspiration (ET), resulting in a climatic gradient that affects cropping system management. The objectives of this study were to determine the interaction of cropping system intensification and climatic gradient (ET) on C and N mineralization and to determine if the presence or absence of crop residue on the soil surface affects C and net N mineralization. Two cropping systems, winter wheat‐fallow (WF) (Triticum aestivium L.) and winter wheat‐corn (sorghum)‐millet‐fallow (WCMF) [Zea mays (L.), Sorghum bicolor (L.) Moench, Panicum milaceum (L.)] were studied at three locations across this aforementioned ET gradient. The treatments had been in place for 8 yrs prior to sampling in the study. These results showed that the more intense cropping system (WCMF) had a higher laboratory C mineralization rate at two of the three locations, which the study concluded resulted from larger residue biomass additions and larger quantities of surface residue and soil residue at these locations (Soil residue is defined as recognizable crop residue in the soil that is retained on a 0.6 mm screen). However, no differences in N mineralization occurred. This is most likely due to more N immobilization under WCMF as compared to WF. Presence or absence of crop residue on the surface of undisturbed soil cores during incubation affected potential C and net N mineralization more than either cropping system or location. Soil cores with the surface residue intact mineralized as much as 270% more C than the same soils where the surface crop residue had been removed. In laboratory studies evaluating the relative differences in cropping systems effects on C and N mineralization, the retention of crop residue on the soil surface may more accurately access the cropping system effects.     

Long-Term Effect of Nitrogen and Tillage Management on Soil Carbon Pools in the Semiarid Northern Great Plains

No-tillage and manure application effect on soil organic carbon (SOC) and total nitrogen (N) concentrations were studied under a 27-year-old 4-year rotation consisting corn (Zea mays L.)-soybean (Glycine max L.)-wheat (Triticum aestivum L.)-field pea (Pisum sativum L.). Under each crop, four applied N treatments were control, annual urea-N applications at the rate of 45 and 89 kg N ha^?1, and composted beef cattle feedlot manure-N at the rate 179 kg N ha^?1 applied once every four year. For each fertilizer treatment, no-till (NT) and conventional till (CT) were compared for basic soil properties, SOC, and total N within 0–15 cm soil. Manure application significantly reduced soil bulk density and increased SOC and total N over urea-N. Particulate organic matter, mineralizable N, and permanganate-oxidizable C fractions significantly related with SOC. Long-term manure additions and no-tillage had potential to improve soil compaction and maintain SOC over chemical fertilizer N and CT.     

Growth,radiation use efficiency and grain yield of wheat as influenced by nitrogen,tillage, and crop residue management

Abstract

Soil organic carbon (SOC) sequestration is one of the major agronomic measures to mitigate green house gas emission, enhance food security, and improve agriculture sustainability. The study, therefore, aimed to evaluate crop growth (CG) and radiation use efficiency in spring wheat (Triticum aestivum L.) treated soil with residue type (RT), that is, cowpea (Vigna unguiculata) as legume (LR), maize (Zea mays L.) as cereal (CR) and no residue (NR) treatment applied (5 t ha^?1) on dry matter basis. The CR was subsequently incorporated with tillage depths (TD), that is, deep (DT?=?35?cm) and shallow (ST?=?15?cm) as main plot treatments. The N was applied in two splits starting from 0 to 160?kg ha^?1 as sub plot treatments. Experiment was conducted in two CG seasons 2009–11 at Agronomy Research Farm, the University of Agriculture Peshawar, Pakistan. Results showed the highest CG and RUE with LR incorporated than CR and/or NR with DT. Increasing N-rate resulted an increase in CG, RUE and biomass of wheat. Residue of LR or CR deeply incorporate into the soil has resulted healthy traits (i.e., tillers- and spikes number), which resulted higher biomass. Nitrogen applied 120?kg ha^?1 resulted in higher CG, RUE and grain yield for treatment LR, followed by CR and the lowest for the NR. Crop of second year showed higher grain yield, which was due to healthy traits including better CG and RUE. The study suggests that CR of LR or CR nature incorporated deep into the soil can optimize crop N-fertilizer demand for optimum production, which protects environment from the excessive use of N application.     

15N studies on the transfer of legume-fixed nitrogen to associated cereals in intercropping systems

Summary An attempt has been made to estimate quantitatively the amount of N fixed by legume and transferred to the cereal in association in intercropping systems of wheat (Triticum aestivum L.) — gram (Cicer arietinum L.) and maize (Zea mays L.) —cowpea (Vigna unguiculate L.) by labelling soil and fertilizer nitrogen with ¹⁵N. The intercropped legumes have been found to fix significantly higher amounts of N as compared with legumes in sole cropping if the intercropped cereal-legume received the same dose of fertilizer N as the sole cereal crop. But when half of the dose of the fertilizer N applied to sole cereal crop was received by intercropped plants, the amount of N fixed by legumes in association with cereals was significantly less than that fixed by sole legumes. Under field conditions 28% of the total N uptake by maize (21.2 kg N ha^–1) was of atmospheric origin and was obtained by transfer of fixed N by cowpea grown in association with maize. Under greenhouse conditions gram and summer and monsoon season cowpea have been found to contribute 14%–20%, 16% and 32% of the total N uptake by associated wheat and summer and monsoon maize crops, respectively. Inoculation of cowpea seeds with Rhizobium increased both the amount of N fixed by cowpea and transferred to maize in intercropping system.     

15N Fertilizer recovery in different tillage–straw systems on a Vertisol in north‐west Mexico

Tillage and residue retention affect nitrogen (N) dynamics and nutrient losses and therefore nitrogen use efficiency (NUE) and crop fertilizer use, however, there is little information about residual fertilizer effects on the subsequent crop. Micro‐plots with ¹⁵N‐labelled urea were established in 2014/2015 on a long‐term experiment on a Vertisol in north‐west Mexico. N fertilizer recovery (NFR) and the effects of residual fertilizer N for summer maize (Zea mays L.) and the subsequent wheat (Triticum durum L.) crop were studied in three tillage–straw management practices (CTB: conventionally tilled beds; PB‐straw: permanent raised beds with residue retention; PB‐burn: permanent raised beds with residue burning). Fertilizer ¹⁵N recovery rates for maize grain across all treatments were low with an average of 11%, but after wheat harvest total recovered ¹⁵N (¹⁵N in maize and wheat straw and grain, residual soil ¹⁵N) was over 50% for the PB‐burn treatment. NFR was lowest in CTB after two cropping cycles (32%). Unaccounted N from applied fertilizer for the maize crop averaged 120 kg ¹⁵N ha^?1 after wheat harvest. However, more than 20% of labelled ¹⁵N was found in the 0–90 cm soil profile in both PB treatments after wheat harvest, which highlights the need for long‐term studies and continuous monitoring of the soil nutrient status to avoid over‐application of mineral N fertilizer.     

WINTER CROPS AS BIOASSAYS OF SOIL NITROGEN-SUPPLYING CAPACITY

Soil nitrogen (N)-supplying capacity bioassays could present alternatives to traditional soil tests. Objectives were to identify winter crops and associated characteristics with bioassay potential. Saint Joseph and Bossier City, LA experiments used randomized complete block designs with factorial N fertilizer and winter crop treatment arrangements. Nitrogen rates were applied to corn (Zea mays L.) in 2004. Unfertilized winter wheat ( Triticum aestivum L.), cereal rye (Secale cereale L.), native winter vegetation, and weed-free winter fallow treatments followed corn. At Saint Joseph, cotton (Gossypium hirsutum L.) followed winter crop treatments. Greater corn N rate consistently increased winter crop biomass and N accumulation, suggesting potential as bioassays, and increased Saint Joseph seedcotton yield. Winter crop-seedcotton yield N-response relationships were non-significant by familywise error rate criteria. However, some winter crop characteristics, such as rye N accumulation, for which a relationship to seedcotton yield closely approached significance, may merit further research as soil N-supplying capacity bioassays.     

Agronomic productivity,nitrogen fertilizer savings and soil organic carbon in conservation agriculture: efficient nitrogen and weed management in maize-wheat system

Conservation agriculture (CA) practice increases agronomic productivity and soil fertility, yet CA stimulate nitrogen (N) immobilization and weed interference during the early periods of implementation. This study focuses on efficient N management by soil testing and optical sensor (GreenSeeker^TM) information; and weed management using brown manuring (Sesbania aculeata co-culture) and herbicide mixtures under CA-based maize (Zea mays L.) – wheat (Triticum aestivum L. emend Fiori & Paol) system in the Indo-Gangetic Plains. Fertilizer N application guided by the optical sensor increased grain yields of maize and wheat up to 20 and 14% (average of two years), respectively, compared to whole N application at sowing. Weed management using brown manuring in maize and herbicide mixtures in wheat increased the grain yields up to 10 and 21%, respectively, over the weedy check. The optical sensor-based N management saved up to 45 and 30 kg N ha^–1 of the optimized N fertilizer rate in maize and wheat, respectively, over whole N application. Fertilizer N management coupled with brown manuring resulted in 5 and 4% higher soil organic carbon accumulation. Implementing efficient N fertilizer and weed management in the early years of CA can improve agronomic yield, fertilizer savings, and soil organic carbon content.     

Cover crop nitrogen availability to conventional and no‐till corn: Soil mineral nitrogen,corn nitrogen status,and corn yield

Abstract

Understanding seasonal soil nitrogen (N) availability patterns is necessary to assess corn (Zea mays L.) N needs following winter cover cropping. Therefore, a field study was initiated to track N availability for corn in conventional and no‐till systems and to determine the accuracy of several methods for assessing and predicting N availability for corn grown in cover crop systems. The experimental design was a systematic split‐split plot with fallow, hairy vetch (Vicia villosa Roth), rye (Secale cereale L.), wheat (Triticum aestivum L.), rye+hairy vetch, and wheat+hairy vetch established as main plots and managed for conventional till and no‐till corn (split plots) to provide a range of soil N availability. The split‐split plot treatment was sidedressed with fertilizer N to give five N rates ranging from 0–300 kg N ha^‐1 in 75 kg N ha^‐1 increments. Soil and corn were sampled throughout the growing season in the 0 kg N ha^‐1 check plots and corn grain yields were determined in all plots. Plant‐available N was greater following cover crops that contained hairy vetch, but tillage had no consistent affect on N availability. Corn grain yields were higher following hairy vetch with or without supplemental fertilizer N and averaged 11.6 Mg ha^‐1 and 9.9 Mg ha^‐1 following cover crops with and without hairy vetch, respectively. All cover crop by tillage treatment combinations responded to fertilizer N rate both years, but the presence of hairy vetch seldom reduced predicted fertilizer N need. Instead, hairy vetch in monoculture or biculture seemed to add to corn yield potential by an average of about 1.7 Mg ha^‐1 (averaged over fertilizer N rates). Cover crop N contributions to corn varied considerably, likely due to cover crop N content and C:N ratio, residue management, climate, soil type, and the method used to assess and assign an N credit. The pre‐sidedress soil nitrate test (PSNT) accurately predicted fertilizer N responsive and N nonresponsive cover crop‐corn systems, but inorganic soil N concentrations within the PSNT critical inorganic soil N concentration range were not detected in this study.     

Effect of organic residue amendments and soil moisture on N mineralization,maize (Zea maysL.) dry biomass and nutrient concentration

Greenhouse pot experiments using four tropical soils were conducted to measure the effect of crop residues on nitrogen mineralization/immobilization and the growth of maize plants under two soil moisture regimes (pF2.5 and pF3.5). Nitrogen-rich residues of pigeon pea [PP, Cajanus cajan (L.) Millps, C/N, 18.8] enhanced plant growth and increased the assimilation of mineral elements (N, P and K) at both moisture regimes. Less nitrogen-rich residues of haricot beans [HB, Phaseolus vulgaris (L.), C/N, 28.9] had a slightly negative effect on plant growth and the assimilation of mineral elements, and a stronger negative effect was recorded for the most N-poor plant residue, maize [M, Zea mays (L.), C/N, 33.6]. For PP, we estimated the recovery of residue-nutrients in maize plants (net increase in N, P and K assimilation due to PP incorporation) as 19% for N, 88% for P and 86% for K in the high-moisture regime (pF2.5). The equivalent values for the drought-stress regime (pF3.5) were 10, 34 and 38%, respectively. The results demonstrate the immediate enhancement of plant growth by plant residues with a low C/N ratio, even under drought-stress conditions.     

NITROGEN,PHOSPHORUS, AND POTASSIUM NUTRIENT EFFECTS ON GRAIN FILLING AND YIELD OF HIGH-YIELDING SUMMER CORN

A three-site-year field experiment was conducted to determine nitrogen (N), phosphorus (P), and potassium (K) fertilizer effects on grain filling dynamics and yield formation of high-yielding summer corn (Zea mays L.) in a wheat (Triticum aestivum L.)-corn double crop cropping system. Application of combined NPK fertilizers resulted in the greatest grain yield, largest grain number and grain weight when compared with the treatments receiving N, NP, or NK. Grain filling rate and duration, grain volume, and grain yield increased with NPK rates; however, doubling the rate of 180 kg N ha^?1, 40 kg P ha^?1, and 75 kg K ha^?1 fertilizer only led to minimal increases in grain filling rate (0.8%), grain filling duration (1.6%), grain volume (1.3%) and grain yield (0.4%). Our results suggested that for the high-yielding summer corn, a combined NPK fertilization is required to enhance grain filling and yield, and that under well-fertilized circumstances, limited increases in both grain filling and sink capacity might be the main factor restricting further yield improvement.     

Soil strength, cotton root growth and lint yield in a southeastern USA coastal loamy sand

Inverse linear relationships between soil strength and yield in Coastal Plain soils that have subsurface genetic hard layers have previously been developed for corn (Zea mays L.), soybean (Glycine max L. Merr.), and wheat (Triticum aestivum L.) grown under management systems that include annual or biannual non-inversion deep tillage. In a field study in the southeastern Coastal Plains of the USA, we tested this relationship for cotton (Gossypium hirsutum L.) grown in wide (0.96 m) rows, hypothesizing that root growth and lint yield of cotton would increase with a decrease in soil strength associated with annual deep tillage or cover crop. Root growth and yield were evaluated for treatment combinations of surface tillage or none, deep tillage or none, and rye (Secale cereale L.) cover crop or none. Root growth increased (r²=0.66–0.68) as mean or maximum soil strength decreased. Cotton lint yield was not significantly affected by the treatments. Lack of yield response to tillage treatment may have been the result of management practices that employed a small (3 m wide) disk in surface-tilled plots and maintained traffic lanes, both of which help prevent re-compaction. These results indicate that less than annual frequency of subsoiling might be a viable production practice for cotton grown in traditionally wide (0.96 m) rows on a Coastal Plain soil (fine loamy Acrisol–Typic Kandiudult). Thus, annual subsoiling, a practice commonly recommended and used, need not be a blanket recommendation for cotton grown on Coastal Plain soils.     

Growth and reproduction of the vermicomposting earthwormPerionyx excavatus as influenced by food materials

An outdoor study was undertaken using polyethylene containers to assess the suitability of different organic residues, soybean straw (Glycine max L. Merril.), wheat straw (Triticum aestivum L.), maize stover (Zea mays L.), chickpea straw (citer arietinum L.) and city garbage, as food for the tropical epigeic earthwormPerionyx excavatus, and to assess the influence of this earthworm on the decomposition of these materials. Maize stover was found to be the most suitable of the food materials used. Population growth ofP. excavatus was enhanced by addition of these organic materials in the temperature range 24°-30°C, while the population was adversely affected above 30°C in a vermiculture system. Addition of earthworms accelerated the breakdown of residues, which ultimately resulted in a lowering of the C:N ratio, water-soluble carbon and carbohydrates, and increased ash percentage and cation exchange capacity compared with their respective controls.     

Ureolytic Activity of Soybean and Corn Residue Extracts

The enzyme urease is responsible for the rapid hydrolysis of urea in agroecosystems where more than 50% of the applied nitrogen (N) can be lost via ammonia volatilization. The objectives of the study were to (1) extract urease from corn (Zea mays L.) and soybean (Glycine max L.) and (2) compare the urease activity from soybean and corn residues to Jackbean (Canavalia ensiformis) urease using Fourier transform infrared spectroscopy (FTI-R). Concentrations of urea and sodium bicarbonate ranging from 0 to 200 mM were analyzed with FTI-R to determine the correlation to peak height. Bicarbonate produced the most responsive peaks to concentration at 1,362 cm^?1. Urease extracted from soybean residue was active, producing a bicarbonate peak at 1362 cm^?1, whereas no urease activity was observed in corn residue. Variation among urease activities in crop residues could suggest a need for more precise nitrogen management in conservation tillage agroecosystems to reduce ammonia volatilization.     

Carbon decomposition kinetics and nitrogen mineralization from corn,soybean, and wheat residues

Abstract

An incubation study was conducted for 30 days in Taloka (fine, mixed, thermic mollic Albaqualf) and Leadvale (fine, silty, siliceous, thermic typic Fragiudult) silt loam soils to evaluate carbon (C) and nitrogen (N) mineralization from soybean [Glycine max (L.) Merr.], corn (Zea mays L.), and wheat (Triticum aestivum L.) residues. Corn and soybean residues were collected at the tasseling and late vegetative stages, respectively. Wheat straw was collected after harvest. Carbon dioxide (CO₂) evolution and inorganic N accumulation were measured. Carbon mineralization was described by a sequential decomposition model with a rapid and slow phase, each described by first‐order kinetics. Rapid and slow fraction rate constants and percent rapid were determined. Decomposition ranged from 39% for wheat to 67% for soybean. Carbon dioxide evolution peaked on the third day, and 30 to 50% of residue C was decomposed during the first six days of incubation. Decomposition and N mineralization were higher in the Taloka compared to the Leadvale soil, and generally followed the sequence soybean > corn > wheat residues as did percent rapid fraction, and rapid and slow fraction rate constants. Rapid fraction rate constants ranged from 0.039±0.005 to 0.115±0.005 per day. Slow fraction rate constants ranged from 0.013±0.002 to 0.030±0.002 per day. Percent rapid fraction ranged from 13±2% to 38±2%. The half‐lives of the slow fraction ranged from 23.4±3.5 to 51.8±3.5 days. Nitrogen mineralization, as estimated by ammonium (NH₄) and nitrate (NO₃) formation occurred only with the soybean residue, whereas the corn and wheat residues were characterized by N immobilization throughout the study.     

Soil Inorganic Nitrogen with Incubation of Rye Cover Crop Biomass

A soil incubation study was conducted to evaluate the effect of winter cereal rye (Secale cereale L.) cover crop (CC) biomass and fertilizer nitrogen (N) addition on soil inorganic-N. Rye aboveground biomass was collected following corn (Zea mays L.) and soybean [Glycine max (L.) Merr.], and incubated at equivalent field temperatures for 105 d at rates of 1120, 2240, and 3360 kg dry matter (DM) ha^?1. Despite N addition from the rye biomass at any rate, there was no real effect on ammonium (NH₄)-N, and only from 63 d to 105 d a limited net increase in nitrate (NO₃)-N and inorganic-N was observed compared to no-rye. Nitrate-N and inorganic-N concentrations change per heat unit (HU) accumulation was negative with rye addition through 7 d, but was positive consistently across the remaining incubation period with or without rye. Overall, the rye CC biomass had only a neutral to small positive effect on soil inorganic-N.