Pulse crops, having the capacity for biological nitrogen (N) fixation, rarely receive N fertilizers, but information is scarce on N balance for pulse crops or pulse crop-spring wheat (Triticum aestivum L.) rotations. The objective of the study was to evaluate N balance based on N inputs and outputs and soil N sequestration rate for pulse crops and pulse crop-spring wheat rotations from 2021 to 2024 in the US northern Great Plains. Pulse crops (chickpea [Cicer arietinum L.], lentil [Lens culinaris Medik.], and pea [Pisum sativum L.]) were rotated with spring wheat to form four crop rotations (chickpea-spring wheat, lentil-spring wheat, pea-spring wheat, and spring wheat-spring wheat). Total N input from N fertilization, biological N fixation, soil N mineralization, crop seed, and precipitation was 9-27% greater for pea than for other crops and greater for pea-spring wheat than chickpea-spring wheat and continuous spring wheat. Total N output from grain N removal, ammonia volatilization, denitrification, plant senescence, leaching, surface runoff, and gaseous emissions was 20-62% greater for spring wheat than pulse crops. Nitrogen sequestration rate at 0-15 cm was 89% greater for spring wheat than lentil and 106-107% greater for pea-spring wheat and spring wheat-spring wheat than lentil-spring wheat. Nitrogen balance was 215-356% greater for chickpea and pea than lentil and spring wheat and 114-118% greater for chickpea-spring wheat and pea-spring wheat than lentil-spring wheat. Greater N input increased N surplus for pea or pea-spring wheat, and greater N output increased N deficit for spring wheat or spring-spring wheat compared to lentil or lentil-spring wheat, indicating that pea alone or in rotation with spring wheat reduced N loss to the environment by increasing soil N storage compared to continuous spring wheat.

Cropping systems can affect greenhouse gas (GHG) emissions due to variations in farm operations, root respiration, and soil organic matter mineralization that need further exploration. We examined the effect of tillage (conventional till [CT] and no-till [NT]) and crop phases (sugarbeet [Beta vulgaris L.] and corn [Zea mays L.]) on CO2, N2O, and CH4 fluxes and GHG balance (GHGB or sum of CO2 equivalents of all GHGs) in an irrigated barley (Hordeum vulgare L.)-sugarbeet-corn-soybean (Glycine max L.) rotation from 2016 to 2020 in the US northern Great Plains. A static chamber method was used to measure GHG fluxes at 3-30 d intervals, depending on crop performance and soil environment, throughout the year. While CO2 peak fluxes occurred mostly during the crop growing season, N2O peak fluxes occurred throughout the year. The CH4 flux was minimal, except for some peaks in October 2017 and January and April 2019. Cumulative CO2 flux from May to April and GHGB were 26-44 % greater for CT with sugarbeet than NT with sugarbeet or corn in 2016-2017 and 24-41 % greater for NT with sugarbeet than CT with corn in 2018-2019 and 2019-2020. Cumulative N2O flux was 70-244 % greater for CT with sugarbeet than NT with sugarbeet in 2016-2017 and 2019-2020 and 38-73 % greater for NT with sugarbeet than other treatments in 2018-2019. Cumulative CH4 flux did not vary among treatments in any year. The GHG emissions can be reduced by using CT with corn and NT with corn and sugarbeet compared with CT with sugarbeet during the dry year and using CT with corn compared with other treatments during the wet year in the barley-sugarbeet-corn-soybean rotation under sandy loam soils of the US northern Great Plains, indicating that treatments effect on reducing GHG emissions varied with climatic conditions.

Carbon footprint and C balance are used to understand whether an agroecosystem is a C source or sink. Our objective was to evaluate C inputs and outputs for determining C balance for pulse crops in rotation with spring wheat (Triticum aestivum L.) from 2021 to 2022 to 2024-2025 in the US northern Great Plains. Pulse crops (chickpea [Cicer arietinum L], lentil [Lens culinaris Medik.], and pea [Pisum sativum L.]) were rotated with spring wheat to form four crop rotations (chickpea-spring wheat, lentil-spring wheat, pea-spring wheat, and spring wheat-spring wheat). Straw C was 26-74% lower for pulse crops than spring wheat, but 19-23% greater for pea-spring wheat than chickpea-spring wheat and lentil-spring wheat. Root biomass and rhizodeposit C were 24-31% greater for spring wheat-spring wheat than chickpea-spring wheat and pea-spring wheat. Grain C was 21% greater for pea than chickpea, but 64-97% lower for pulse crops than spring wheat. Cumulative CO2 flux from May to April was 14-17% greater for spring wheat-spring wheat than chickpea-spring wheat and lentil-spring wheat. Soil C sequestration rate was greater for pea and spring wheat than chickpea and lentil, or greater for pea-spring wheat and spring wheat-spring wheat than other crop rotations. Carbon balance was 5-16% lower for pulse crops than spring wheat, or 9-16% lower for pulse crop-spring wheat rotations than spring wheat-spring wheat. Because of greater C input and C sequestration rate, spring wheat can reduce C loss compared to pulse crops, or continuous spring wheat can reduce the loss compared to pulse crop-spring wheat rotations.

Balancing food security and climate change mitigation has been a global priority, yet viable pathways to achieve both simultaneously remain elusive. The dual potential of cover crops (CCs) to increase soil organic carbon (SOC) and succeeding crop yield was evaluated by meta-analysis of 1396 paired observations globally. Outcomes were Win-Win (+, +), Trade-off 1 (+, -) Trade-off 2 (-, +), and Lose-Lose (-, -) in 68.9%, 16.4%, 9.0%, and 5.7% of the observations, respectively. The synthetic intensity for the responses of SOC and crop yield to CCs was controlled by CC biomass, tillage practice, establishment years, and nitrogen rate. Global optimal window to maximize co-benefits included CC biomass < 7.65 t ha -1 , duration > 4 years, adoption of legume CCs and conservation tillage, and reduced N input. Specifically, CCs had a large Win-Win potential in rice systems and arid regions with low inherent SOC content. Emphasizing context-specific CC management strategies that promote Win-Win and minimize Trade-off or Lose-Lose conditions can reconcile historical contradictions over yield–SOC trade-offs and support the dual goal of enhancing climate mitigation and food security.

The reduced N fertilization rate and N supplied by pea (Pisum sativum L.) residue may sustain subsequent spring wheat (Triticum aestivum L.) growth, yield, and quality. We examined the response of spring wheat growth, yield, and quality to cropping systems and N fertilization rates from 2012 to 2019 in the US northern Great Plains. Cropping systems were conventional till spring wheat–fallow (CTWF), no-till spring wheat–fallow (NTWF), no-till spring wheat–pea (NTWP), and no-till continuous wheat (NTCW), and N fertilization rates to spring wheat were 0, 50, 100, and 150 kg N ha−1. Wheat plant density and straw yield were 13–100% greater for CTWF and NTWF than NTWP and NTCW in most years. Wheat grain yield and protein concentration were also 15–115% greater for CTWF and NTWF than other cropping systems at most N fertilization rates and years. In contrast, wheat grain test weight was 1–2% lower for CTWF and NTWF at most N fertilization rates and years. Increasing N fertilization rate mostly increased grain yield and protein concentration but reduced grain test weight for most cropping systems and years. Although CTWF and NTWF with or without N fertilization increased wheat yield and quality, these practices are not sustainable due to reduced annualized yield, soil health, and environmental quality. Because of similar or greater grain yields and test weights among NTWP with 50 kg N ha−1 and NTWP and NTCW with other N rates, NTWP with reduced N rates may sustain spring wheat yield and grain size but not grain protein in the northern Great Plains.

Pulse crops are becoming more popular to replace summer fallow in the conventional crop-fallow systems for increased crop yields, but limited information exists on the performance of pulse crops and succeeding crop yields and N dynamics in the US northern Great Plains. The objective of the study was to determine plant density, straw and grain yields, grain protein concentration, N uptake, harvest index (HI), N harvest index (NHI), N-use efficiency (NUE), and N removal index (NRI) of three pulse crops (chickpea [Cicer arietinum L.], lentil [Lens culinaris Medik], and pea [Pisum sativum L.]) and one control (spring wheat) as well as succeeding spring wheat in the rotation from 2021 to 2024. Plant density was 70%-203% greater for lentil than chickpea and pea but was 58% lower than spring wheat. Straw and grain yields and N uptake were 10%-68% greater for pea than chickpea and lentil, but yields were 25%-63% lower for pea than spring wheat. Grain protein concentration was 14%-20% greater for pea and lentil than chickpea and 27%-51% greater for pulse crops than spring wheat. The HI and NHI were 5%-25% greater for chickpea and lentil than pea and spring wheat. Spring wheat straw and grain yields, NUE, and NRI following pulse crops were 11%-21% greater than following continuous spring wheat. Because of greater grain yield and protein concentration, pea is recommended as the most effective pulse crop to replace summer fallow and increase crop yields and quality in crop-fallow systems in the northern Great Plains.

Cover crop and N fertilization rate to malt barley ( Hordeum vulgare L.) (NRMB) can affect soil residual NO 3 ‐N that may alter pea ( Pisum sativum L.) growth, yield, and quality in the malt barley–pea rotation. The effect of cover crop (oat [ Avena sativa L.) cover crop vs. none) and NRMB (0, 40, 50, 60, 70, and 80 kg N ha −1 ) were examined on soil residual NO 3 ‐N and pea growth, yield, and quality in the malt barley–pea rotation from 2014 to 2019 in the US northern Great Plains. Soil residual NO 3 ‐N content increased with increasing NRMB. Cover crop biomass yield was 33%–393% greater with than without NRMB in 2015 and 2016. Pea grain yield and N uptake were 40%–41% greater for 40 than 60 kg N ha −1 of NRMB in 2015 and 45%–167% greater for 70 than 0 kg N ha −1 in 2018. Grain test weight was 27% greater with than without NRMB in 2014 and 2019. Harvest index was 22%–29% greater for 70 than 40, 60, and 80 kg N ha −1 in 2014, but 18%–33% greater for 0 than 50 or 80 kg N ha −1 in 2017 and 2019. Nitrogen harvest index was 13%–14% greater for 0 than 50 and 60 kg N ha −1 in 2015 and 2019. Straw yield, N concentration, N uptake, and grain protein concentration were 10%–34% greater with than without NRMB. Nitrogen fertilization to malt barley enhanced pea yield and quality, regardless of cover cropping, in the malt barley–pea rotation in the northern Great Plains.

Information is needed on greenhouse gas (GHG) emissions due to tillage and crop type on sugarbeet (Beta vulgaris L.)-based crop rotations. We measured CO2, N2O, and CH4 emissions as affected by tillage (conventional till [CT], no-till [NT], and strip till [ST]) under sugarbeet and spring wheat (Triticum aestivum L.) phases of an irrigated sugarbeet-pea (Pisum sativum L.)-spring wheat rotation from 2018 to 2021 in the US northern Great Plains. Greenhouse gases were measured using a static chamber at 3- to 28-day intervals, depending on plant growth and environmental conditions, throughout the year. The CO2 and N2O fluxes peaked for 2-8 months immediately after tillage, planting, fertilization, intense precipitation, and irrigation. The CH4 flux varied little, except for some peaks in the first year. Cumulative annual CO2 flux was 19%-30% greater for CT than NT in 2019-2020 and 2020-2021, and 13% greater for CT than ST in 2020-2021. Cumulative N2O flux was 31%-36% greater for CT than ST in 2018-2019 and 2020-2021, but 33%-83% lower for sugarbeet than spring wheat in all years. Cumulative CH4 flux was 83% lower for CT than NT and 68% lower for sugarbeet than spring wheat in 2018-2019. The GHG balance was 15%-23% greater for CT than NT and ST in 2019-2020 and 2020-2021 and 31% greater under sugarbeet than spring wheat in 2018-2019. No-tillage can reduce GHG emissions compared to conventional tillage, and sugarbeet can reduce N2O emissions compared to spring wheat in sugarbeet-based crop rotations.

The effect of long-term no-till dryland crop rotations in sequestering C and N in the soil to enhance soil health and environmental quality and crop yields in arid and semiarid regions needs further exploration. We studied the effect of no-till dryland crop rotations and sequence of crops in the rotation on crop residue C and N inputs and soil total C (STC), soil total N (STN), and NH4-N and NO3-N contents at the 0–120 cm depth as well as crop yields and N-use efficiency (NUE) from 2012 to 2022 in the US northern Great Plains. Crop rotations and sequences included durum (Triticum turgidum L., D) with camelina (Camelina ceantz L., C), pea (Pisum sativum L., P), napus (Brassica napus L., N), and safflower (Carthamaus tinctorius L., S) as well as continuous durum. Residue C was 10–34

Cover cropping is an effective agricultural management strategy for enhancing soil organic carbon (SOC) sequestration and mitigating climate change. However, the contribution of different cover crop species to individual carbon (C) fractions in soil remains unclear. An in-situ decomposition experiment using C-13-labeled residues of soybean (SB) or sudangrass (SG), along with a control with no residue (CK), was designed to explore the dynamics of residue decomposition, distribution of cover crop-derived C into aggregate-protected and -unprotected C, and the sequestration mechanisms of these fractions. The aggregate-protected C included intra-aggregate particulate organic C (iPOC) and mineral-associated organic C (MAOC), and aggregate-unprotected C included coarse particulate organic C (cPOC) and free fine particulate organic C (fPOC). The amount and rate of cover crop residue C mineralization were greater in SB than in SG across all wheat-growing stages. The SB increased large macroaggregate (>2 mm) compared to SG during the early wheat growth stages. The aggregate-protected C fractions were greater in SB and SG than CK at the pre-sowing, tillering, and heading stages. The C-13 labeling indicated that C sequestration occurred primarily as aggregate-protected C, predominantly as MAOC. The recovery efficiencies of cover crop-derived C into soil C fractions fell below 0 % at green-up and jointing stages. At maturity stage, the cumulative C recovery rate of cover crop-derived C into SOC was greater in SB (16.3 %) than in SG (8.76 %). Correlation analysis indicated that cover cropping promoted SOC sequestration primarily and directly by increasing the aggregate-protected C. Structural equation model analysis suggested that SG sequestered C into soils primarily by increasing cPOC and iPOC, In contrast, SB sequestered C by increasing cPOC, iPOC, and MAOC. This study elucidates the dynamic effects of cover cropping on soil C during wheat growth and the distinct C sequestration mechanisms in legume and non-legume systems.

Cultivation of maize (Zea mays L.) can emit significant greenhouse gases (GHGs) due to root respiration, soil organic matter decomposition, and fertilizer losses in a tropical environment. Our objective was to examine the effect of tillage (conventional tillage [CT], minimum tillage [MT], and no-tillage [NT]), N fertilization rate (0, 90, and 120 kg N ha(-1)), and manure application rate (0, 5, and 10 Mg ha(-1)) on CO2, N2O, and CH4 emissions under maize in two growing seasons (July-October 2018 and May-August 2019) in southwest Nigeria. We measured CO2, N2O, and CH4 fluxes using the static chamber method and soil temperature and water content weekly, global warming potential (GWP), maize yield, and greenhouse gas intensity (GHGI). The CO2 and N2O fluxes peaked immediately following planting, fertilization, and intense precipitation, with most fluxes concentrated at 2-6 wk after planting. The CH4 flux showed little change throughout the duration of the study. Cumulative CO2 and N2O fluxes were greater for CT and MT than NT, but cumulative CH4 flux was greater for MT than CT and NT. Higher N fertilization rate increased N2O and CH4 fluxes. The GWP was greater for CT than MT and NT and greater for 90 than 0 kg N ha(-1). Maize yield was greater for MT than CT and NT and increased with higher N fertilization rate. The GHGI was lower for MT than CT and lower for 120 than 0 and 90 kg N ha(-1). Because of overall lower maize yield, MT with reduced N ferilization rate in split applications may be needed to reduce GHG emissions while sustaining yield in the sandy soils of southwest Nigeria.

Tillage practices can significantly impact soil structure and pore size distribution and connectivity, consequently affecting the shape of the soil water retention curve (SWRC) and its related estimated hydraulic parameters in the top layer of soil. This study investigated the effect of no-tillage (NT) and conventional tillage (CT) practices on SWRCs and their soil hydraulic parameters, estimated by the Brooks–Corey (BC) function at 0–15 and 15–30 cm depths within sugarbeet and corn planting rows in clay loam and sandy loam soils, respectively. Soil water retention curves were measured using the evaporative method (HYPROP). Measured SWRC results were modeled for both untilled and tilled soils using the BC function for each depth in both soils. In clay loam, results indicated that all soil parameters of the BC function, water contents at 330 (θ330) and 15,000 (θ15,000) hPa, and plant available soil water content (AW) were not significantly affected by the type of tillage at either soil depth. The lack of difference in results between NT and CT may be due to considerable soil disturbance, primarily by the harvest process of sugarbeet roots. However, in sandy loam, results indicated that differences occurred in SWRC’s estimated parameters between the NT and CT practices. Averaged across 4 years and two soil depths, the pore size distribution index (λ) and saturated water content (θs) were significantly larger under CT than under NT due to greater soil loosening and disturbance caused by multiple passes of the CT process, thereby developing more soil macroporosity. However, the θ330 and AW were significantly larger in NT than in CT due to reduced soil disturbance and improved soil structure under NT compared to CT practices. Regardless of tillage, measurements of SWRC are important for determining better irrigation management practices, enabling producers to optimize crop productivity, while saving water and sustaining water quality.

Little information exists about greenhouse gas (GHG) emissions under perennial bioenergy crops (PBCs) with various N fertilization rates. Our objectives were to evaluate the effect of PBCs receiving various N fertilization rates on N 2 O and CH 4 emissions, GHG balance (GHGB), and yield‐scaled GHGB (YSGB) and compare them with an annual crop from 2012–2013 to 2013–2014 in the northern Great Plains. The PBCs were intermediate wheatgrass (IW, Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass (SB, Bromus inermis L.), and switchgrass (SG, Panicum virgatum L.), and N fertilization rates were 0, 28, 56, and 84 kg N ha −1 . The annual crop was spring wheat (WH, Triticum aestivum L.) with 80 kg N ha −1 . The N 2 O flux peaked immediately after planting, fertilization, intense precipitation (>15 mm), and snowmelt. Cumulative N 2 O flux was greater for SG than IW and SB with 56 kg N ha −1 in 2012–2013 and with 28–84 kg N ha −1 in 2013–2014. The CH 4 flux was not affected by treatments. Carbon sequestration rate at 0–30 cm from 2009 to 2019 was greater for IW than other PBCs. The GHGB and YSGB were greater for SG and SB than IW with almost all N fertilization rates in both years. Comparing PBCs and an annual crop, cumulative N 2 O flux, GHGB, and YSGB were greater for SG than IW, SB, or WH in 2013–2014. The IW can reduce GHG emissions per unit area and per unit crop yield compared to other PBCs and WH.

Reduction in N fertilization rate due to N supplied by pea ( Pisum sativum L.) may enhance soil C and N in the malt barley ( Hordeum vulgare L.)–pea rotation. The effect of winter cover cropping (oat [ Avena sativa L.] vs. none) and N fertilization rate (0, 40, 50, 60, 70, and 80 kg N ha −1 ) for malt barley (NR) was evaluated on soil C and N stocks at the 0‐ to 120‐cm depth from 2013 to 2019 in the dryland malt barley–pea rotation in the US northern Great Plains. Carbon and N stocks were soil total C (STC), soil organic C (SOC), soil inorganic C (SIC), and soil total N (STN). Cover crop C and N were greater for 40 kg N ha −1 than other NRs and crop residue C and N were greater in 2016 than other years. The STC and SOC at 0–15 and 15–30 cm increased by 0.02 and 0.06 Mg C ha −1 kg −1 N in 2016 and 2019, respectively ( p ≤ 0.10). The STC at 0–15 and 15–30 cm was greater at 40 than 50 and 70 kg N ha −1 in 2019. The STN at 15–30 cm increased by 0.004 Mg N ha −1 kg −1 N with than without cover cropping. The STC, SOC, and STN at 0–15 and 15–30 cm also increased at greater rates from 2013 to 2019 with than without cover cropping ( p ≤ 0.10). Cover cropping with reduced N fertilization rate for malt barley (NR) can enhance soil C but not soil N stock at surface layers in the malt barley–pea rotation.

Innovative management practices are needed to mitigate greenhouse gas (GHG) emissions from the agricultural sector by enhancing soil carbon (C) and nitrogen (N) stocks, which serve as major reservoirs of C and N in the terrestrial ecosystem. The effect of cropping systems and N fertilization rates were examined on soil organic C (SOC) and soil total N (STN) stocks at the 0–120 cm depth from 2011 to 2018 in a dryland farm in the US northern Great Plains. Cropping systems were no-till continuous spring wheat (Triticum aestivum L.) (NTCW), no-till spring wheat–pea (Pisum sativum L.) (NTWP), no-till spring wheat–fallow (NTWF), and conventional till spring wheat–fallow (CTWF) and N fertilization rates were 0, 50, 100, and 150 kg N ha−1 applied to spring wheat. The SOC and STN were greater for NTWP than other cropping systems at most N fertilization rates and depth layers. Increasing N fertilization rate increased SOC at 0–30 cm for NTWP and NTCW, but had a variable effect on STN for various cropping systems and soil depths. The NTWP with 50–100 kg N ha−1 can enhance SOC and STN at 0–30 cm compared to other cropping systems and N fertilization rates in the US northern Great Plains.

Information is needed on the effect of long-term cropping systems on greenhouse gas (GHG) emissions in dryland conditions. The effect of 34 years of dryland cropping system was examined on N2O and CH4 emissions, greenhouse gas balance (GHGB), crop yield, and yield-scaled GHG balance (YSGB) from 2016-2017 to 2017-2018 in the US northern Great Plains. Cropping systems were no-till continuous spring wheat (Triticum aestivum L.) (NTCW), no-till spring wheat-pea (Pisum sativum L.) (NTWP), and conventional till spring wheat-fallow (CTWF). Gases were sampled twice a week to once a month throughout the year using a static chamber and flux determined. Soil C sequestration rate at 0-10 cm was determined from samples taken in 2012 and 2019. The N2O emissions occurred immediately after planting, fertilization, and intense rainfall from May to September in both years when the emissions greater for NTCW and NTWP than CTWF. The CH4 emissions were minimal and mostly negative throughout the year. Carbon sequestration rate was positive for NTCW and NTWP due to greater C input, but negative for CTWF due to rapid C mineralization. As a result, GHGB was 170%-362% lower for NTCW than NTWP and CTWF. Annualized crop yield was 23%-60% greater for NTWP than NTCW and CTWF in 2016-2017, but not different among cropping systems in 2017-2018. The YSGB was also 129%-132% lower for NTCW and NTWP than CTWF in both years. Because of greater annualized crop yield, but lower GHG emissions, NTWP is recommended for reducing GHG emissions while sustaining long-term dryland crop yields in the northern Great Plains.

Carbon footprints from plants, soil, and the environment are needed to evaluate C balance of an agroecosystem, which indicates if a system is a C source or sink for mitigating climate change. There is scarce information about C footprint and C balance in dryland agroecosystems. We measured C storage of above‐ and belowground crop biomass, CO2 fluxes, soil C sequestration rates, and C balances of three long‐term (34‐year‐old) dryland cropping sequences from 2016 to 2018 in the US northern Great Plains. Cropping sequences were no‐till continuous spring wheat (NTCW; Triticum aestivum L.), no‐till spring wheat–pea (NTWP; Pisum sativum L.), and conventional till spring wheat–fallow (CTWF). Carbon storage in grain, straw, root, and rhizodeposit were 29%–61% greater for NTCW and NTWP than CTWF. The CO2 flux peaked immediately after tillage, planting, fertilization, and intense precipitation (>10 mm) for 3 months in 2016–2017. Cumulative annual CO2 flux was 8%–37% greater for NTCW than NTWP and CTWF in 2016–2017, but was not different among cropping sequences in 2017–2018. Soil C sequestration rate at 0–10 cm measured from 2012 to 2019 was in the order: NTCW (0.27 Mg C ha−1 year−1) > NTWP > CTWF (−0.23 Mg C ha−1 year−1). Carbon balance remained negative and was not significantly different among cropping sequences but varied by year. Carbon loss increased with increased precipitation, regardless of cropping systems. Although a C source, the legume–nonlegume rotation can reduce C loss due to greater grain C output than other cropping sequences in the semiarid region of the northern Great Plains.

Cover crops protecting soil erosion during the summer fallow in the monsoon weather may enhance dryland winter wheat yield and N relations. We examined the effects of four summer cover crops (soybean (Glycine max L., SB), sudangrass (Sorghum sudanense {Piper} Stapf, SG), soybean and sudangrass mixture (SS), and no cover crop (CK)) and three N fertilization rates (0, 60, and 120 kg N ha−1) on winter wheat yield, quality, and N relations from 2017–2018 to 2020–2021 in the Loess Plateau of China. Cover crop biomass and N accumulation, soil mineral N, and winter wheat yield, protein concentration, and N uptake were greater for SB and SS than other cover crops at most N fertilization rates and years. The N fertilization rate had variable effects on these parameters. Winter wheat aboveground biomass and grain N productivities were greater for CK than other cover crops at all N fertilization rates and years. Nitrogen balance was greater for SS than other cover crops at 60 and 120 kg N ha−1 in all years. The SS with 120 kg N ha−1 can enhance soil mineral N, winter wheat yield and quality, and N balance compared to CK and SG with or without N fertilization rates.

Perennial bioenergy crops may enhance microbial community structures due to their extensive root system compared to annual crops. However, the long-term effect of perennial bioenergy crops receiving different N fertilization rates on microbial community structures is not well defined. We evaluated the 11-year effect of perennial bioenergy crops with various N fertilization rates as well as an annual crop with the recommended N rate on soil microbial properties in 2019 and 2020 in the US northern Great Plains. Perennial grasses were intermediate wheatgrass, IWG (Thinopyrum intermedium [Host] Barkworth and Dewey), and switchgrass, SG (Panicum virgatum L.), with N fertilization rates of 0, 28, 56, and 84 kg N ha−1, and the annual crop was spring wheat, WH (Triticum aestivum, L.) with 80 kg N ha−1. The total fungal phospholipid fatty acid (PLFA) proportion and fungal/bacterial ratio were significantly lower under annual spring wheat than perennial grass (SG). Increased N fertilization rate linearly increased Gram-positive bacterial PLFA proportions and the Gram-positive/Gram-negative bacterial ratio for IWG in 2020 but decreased the PLFA proportions of arbuscular mycorrhizal fungi (AMF) for both perennial bioenergy crops in all years. The proportions of AMF neutral lipid fatty acid and Gram-negative bacterial PLFA were greater for SG (0.432 and 0.271, respectively) than IWG (0.339 and 0.258, respectively), but actinomycetes and the Gram-positive/Gram-negative bacterial ratio were greater for IWG (0.160 and 1.532, respectively) compared to SG (0.152 and 1.437, respectively). Microbial community structures varied with perennial bioenergy crops, N fertilization rates, and perennial vs. annual crops. This study showed how perennial crops favored fungal growth and how annual crops enhanced bacterial growth impacting soil biological health.

Tillage practices significantly impact soil structure, pore-size distribution (PSD), and soil-water retention curves (SWRC). The SWRC, which represents the relationship between soil water content and soil water potential, is important for various studies involving plants, soil, environment, irrigation, drainage, modeling, and hydrology. In this study, the HYPROP method was used to measure SWRCs and estimate soil physical and hydraulic properties under conventional tillage (CT), strip tillage (ST), and no-tillage (NT) systems in clay loam soil. Undisturbed soil cores were collected from 0–15 cm and 15–30 cm depths within sugarbeet rows, with sampling replicated five times following a randomized block design. Soil-water retention curves were modeled using the van Genuchten (vG) model for each depth under each tillage system. The results showed that none of the soil parameters from the vG equation, plant-available soil water content, or pore-size distribution were significantly influenced by tillage type. This lack of significant difference may be attributed to considerable soil disturbance from sugarbeet root harvesting, freeze and thaw cycles between tillage and sampling, or soil displacement caused by beet root growth. However, small differences in soil parameters among the three tillage systems were noted at both soil depths, due to minor variations in soil porosity and pore-size distribution. Regardless of the tillage system, understanding SWRC is essential for insights into soil and water processes such as water flow, soil water storage, and water availability for plants.