Benefits and tradeoffs of reduced tillage and manure application methods in a Zea mays silage system.

Core Ideas Low‐producing alfalfa and tall fescue stands can benefit from the addition of manure. Injection of manure (slicing of soil) did not reduce yields of alfalfa or tall fescue. Impact of manure injection on N 2 O emissions is weather and species dependent. When injection of manure does not increase yield, surface application is more economical. Injecting manure can preserve N, but may mechanically damage the root systems of hay crops such as tall fescue ( Festuca arundinacea L.) and alfalfa ( Medicago sativa L.). Such damage could result in reduced yield. The objective of this study was to compare the effect of disk‐injected versus surface applied liquid dairy manure on (i) alfalfa and tall fescue dry matter (DM) yield and (ii) nitrous oxide (N 2 O) emissions. Two manure application methods (injection versus surface application) and two no‐manure controls (injection versus no soil disturbance) were replicated six times in 2014 and 2015 on established hay stands. Manure application increased alfalfa yield from 2.9 to 3.7 and from 4.2 to 5.1 Mg DM ha ‐1 in 2014 and 2015, respectively, regardless of application method, suggesting no yield penalty or benefit from injection. Nitrous oxide emissions increased two‐ and six‐fold with manure addition, consistent with higher yields under manure application. Compared with the control treatments, manure addition to tall fescue increased yield by 0.8 and 3.3 Mg ha ‐1 in 2014 and 2015, respectively, also with no yield benefit or penalty from injection. Injection of manure did not influence N 2 O emissions in 2014, but increased emissions by 35% compared with surface application in 2015, and this is consistent with differences in soil moisture that year. Our results indicate injection of liquid manure can be implemented without negatively influencing yield in hay crops, while the impact on N 2 O emissions can be crop and weather dependent. When injection does not increase yield, the surface application of manure to hay crops is more economical.

Core Ideas Manure injection increased N 2 O emissions vs. broadcast and broadcast + plow application. Winter thaws increased N 2 O and CO 2 emissions, particularly in soils injected with manure. The impacts of manure application decisions may extend beyond the growing season to influence N 2 O and CO 2 fluxes during winter thaw events. Climate and agricultural management are strong drivers of greenhouse gas (GHG) emissions, but little is known about potential interactions among these drivers. Climate change will likely increase the frequency of wintertime thaws in northern agricultural systems, which have been shown to induce large pulses of carbon dioxide (CO 2 ) and nitrous oxide (N 2 O). We tested the hypothesis that different manure application practices would interact with thaw events to produce GHG emission pulses of different sizes. Specifically, we expected manure injection would increase CO 2 and N 2 O emissions relative to other manure application methods by enhancing subsurface microbial substrate availability. We conducted a laboratory incubation study with frozen, intact soil cores from a continuous corn ( Zea mays L.) system under three manure application methods: broadcast, broadcast + plow, and injection. Cores were subjected to three temperature treatments over 8 d: frozen (−7°C), freeze–thaw (alternating −7 and 5°C), and thaw (5°C). In the freeze–thaw and thaw treatments, cumulative N 2 O emissions were 2 to 20 times greater in injected versus broadcast treatments (6.5 mg N 2 O‐N m –2 averaged across broadcast treatments); cumulative CO 2 emissions were up to two times higher in injected versus broadcast treatments (1017 mg CO 2 –C m –2 averaged across broadcast treatments). Our results suggest that the impacts of manure application choices extend beyond the growing season to increase N 2 O and CO 2 emissions during wintertime thaws, potentially interacting with a warming climate to increase GHG emissions.

Simple SummaryMinimizing the effects of climate change by reducing GHG emissions is crucial and can be accomplished by truly understanding the carbon footprint phenomenon. This study aims to improve the understanding of carbon footprint alteration due to agricultural management and fertility practices. It provides a detailed review of carbon footprint management under the impacts of environmental factors, land use, and agricultural practices. The results show that healthy soils have numerous benefits for the general public and especially farmers. These benefits include being stable and resilient, resistant to erosion, easily workable in cultivated systems, good habitat for soil micro-organisms, fertile and good structure, large carbon sinks, and hence lower carbon footprint. Intensive tillage is harmful to soil structure by oxidizing carbon and causing GHG emissions. If possible, no-till; if not, minimum tillage frequency and depth of tillage, and optimum moisture are recommended. The soil should be at an appropriate level of moisture when tillage takes place. Diverse cropping systems are better for the soil than monocultures. Minimizing machinery operations can help to avoid soil compaction. Building soil organic carbon in the most stable form is the most efficient practice of sustainable crop production.Global attention to climate change issues, especially air temperature changes, has drastically increased over the last half-century. Along with population growth, greater surface temperature, and higher greenhouse gas (GHG) emissions, there are growing concerns for ecosystem sustainability and other human existence on earth. The contribution of agriculture to GHG emissions indicates a level of 18% of total GHGs, mainly from carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Thus, minimizing the effects of climate change by reducing GHG emissions is crucial and can be accomplished by truly understanding the carbon footprint (CF) phenomenon. Therefore, the purposes of this study were to improve understanding of CF alteration due to agricultural management and fertility practices. CF is a popular concept in agro-environmental sciences due to its role in the environmental impact assessments related to alternative solutions and global climate change. Soil moisture content, soil temperature, porosity, and water-filled pore space are some of the soil properties directly related to GHG emissions. These properties raise the role of soil structure and soil health in the CF approach. These properties and GHG emissions are also affected by different land-use changes, soil types, and agricultural management practices. Soil management practices globally have the potential to alter atmospheric GHG emissions. Therefore, the relations between photosynthesis and GHG emissions as impacted by agricultural management practices, especially focusing on soil and related systems, must be considered. We conclude that environmental factors, land use, and agricultural practices should be considered in the management of CF when maximizing crop productivity.

Climate-smart management for increasing crop yield and reducing greenhouse gas emission in Beijing-Tianjin-Hebei region, China

As manure injection methods vary with modifications in application equipment, the availability of manure‐N is probably altered. This study was conducted to quantify differences in the concentrations of inorganic (nitrate and ammonium) soil N and corn (Zea mays L.) yield as affected by vertical knife (VK) and horizontal sweep (HS) injection systems, and broadcast (BCST) applications. These manure application methods, plus a VK injection with nitrapyrin, were compared at a single manure rate at seven locations in Minnesota in 1992 and 1993. Soil inorganic N was measured at growth stages V1 and V4 and after grain harvest. Corn grain yield was also determined. At the V1 growth stage, inorganic‐N from 0 to 2 ft depth averaged 24% higher in the manured treatments than in the nonmanured, unfertilized control. The average of the VK and HS treatments had 10% more inorganic‐N than the BCST treatment and the HS resulted in 7% more inorganic‐N than the VK. At the V4 growth state, similar results were measured—with the HS treatment having 8% more inorganic‐N than the VK treatment. The impact of manure application methods on nitrate‐N was greater than on ammonium‐N for both in‐season samplings. The use of HS resulted in significantly greater nitrate‐N early in the growing season than did VK injection. Grain yields paralleled soil nitrate‐N levels; average yields for the N responsive sites were 85, 107, 115, and 123 bu/acre for the control, BCST, VK, and HS treatments, respectively. While the use of nitrapyrin with VK injection delayed nitrification, the effect on yield was inconsistent.Research QuestionManure application equipment manufacturers have developed numerous methods for applying liquid manure. As manure application methods vary, there may be differences in nutrient release, especially N. The primary objective of our research was to determine the effect of manure application method on inorganic N in the soil profile and on corn grain yield.Literature SummaryWhile volatilization losses of N can be minimized by injecting manure, denitrification can be a significant N loss pathway for injected liquid manure. Research from Illinois, based on soil inorganic N measurements, has indicated that horizontal placement of manure beneath the soil surface could alleviate the potential for denitrification and possibly increase nitrification.Study DescriptionField studies were conducted at seven sites in south‐central and west‐central Minnesota in 1992 and 1993. Application methods for liquid dairy and swine manure included nonincorporated broadcast (BCST), vertical knife (VK) injection, VK injection with nitrapyrin, and horizontal sweep (HS) injection. Soil samples were collected twice early in the growing season and again after harvest to measure inorganic N, and corn grain yields were determined.Applied QuestionWhat effect does manure application method have on soil inorganic N quantity early in the growing season?Broadcast application of manure resulted in the lowest soil (nitrate + ammonium)‐N concentrations at both in‐season sampling times when compared with injected manure treatments (Fig. ). Injecting manure, VK or HS, resulted in greater inorganic‐N concentrations than broadcasting manure, with HS resulting in more inorganic‐N in the soil than VK. The use of the nitrification inhibitor with VK delayed nitrification and had similar amounts of inorganic‐N compared with HS at the V4 growth stage.The effect of liquid manure application methods on corn grain yield and soil inorganic‐N measured in the 0–2 ft depth at V1 and V4 growth stage.imageWere corn grain yields affected by manure application methods?Mean corn grain yield responses were similar to the inorganic‐N concentrations measured in the soil due to manure application methods (Fig. ). For the N responsive sites, the greatest yields (123 bu/acre) were measured with the HS treatment. This was significantly higher than the VK treatment (115 bu/acre). While there was considerable variation across location, there were no significant differences in grain yield due to adding nitrapyrin to the VK treatment. Whereas the BCST method yielded significantly more than the control, it was inferior to all injected application methods.RecommendationsWe recommend the use of HS injectors for liquid manure applications. This method of application provided the greatest amount of nitrate‐N during the early growing season as well as the greatest yield. While the VK injection system with nitrapyrin also resulted in large quantities of nitrate‐N during the growing season, the inconsistency in yields with VK methods limits its widespread endorsement.

Energy use and greenhouse gas emissions in organic and conventional grain crop production: Accounting for nutrient inflows

The practice of straw returning to agricultural fields (SRF) affects crop yields and greenhouse gas (GHG) emissions. However, the responses of crop yields and GHG emissions vary significantly due to diverse climatic conditions, soil conditions, and field management practices. In this study, we conducted a meta-analysis to assess the effects of SRF on the crop yield and GHG emissions from staple crops in China. Our results indicate that the average increment in the yield of three staple crops is 13.00% with SRF. Moreover, SRF decreased the N2O emissions compared to those without straw returning in regions with 800–1200 mm of MAP, SOC > 20 g kg–1, 0.9–1.5 g kg–1 TN, pHs of 6.5–7.5, and a SRF duration < 3 years, in rice cultivation systems, and with partial SRF. However, irrespective of the climatic conditions, soil properties, or field management practices, SRF increased the CO2 emissions compared to those without straw returning. Additionally, while SRF significantly increased the CH4 emissions in paddy fields, it had no discernible effect on the CH4 uptake in upland fields compared to that without straw returning. These findings offer valuable insights for optimizing straw management practices and reducing GHG emissions in farmland ecosystems.

Greenhouse gas emissions and crop yield in no-tillage systems: A meta-analysis

The shift towards renewable energy sources (RES) is crucial for promoting sustainable growth in the EU, aiming to achieve at least a 42.5% contribution of RES to gross final energy consumption by 2030. The transportation sector must also adhere to emission reduction targets, owing to its significant contribution to greenhouse gas (GHG) emissions. This research examines the GHG emissions linked to the cultivation of feedstocks for biofuel production in Poland, specifically analysing wheat, triticale, rye, and maize. To assess and delineate the GHG emissions throughout the lifecycle of biomass production on selected Polish farms, the methodology endorsed by the Polish certification framework for sustainable biofuels and bioliquids (KZR INiG system) was employed, as validated by the European Commission. Data were gathered from 294 questionnaires distributed across large-scale agricultural operations in 91 diverse locations throughout Poland. Findings reveal that emissions varied from 14.3 g CO2eq∙kg−1 for maize to 386.5 g CO2eq∙kg−1 for triticale. The highest average emissions were recorded for wheat at 115.0 g CO2eq∙kg−1, followed closely by rye at 113.8 g CO2eq∙kg−1, triticale at 108.7 g CO2eq∙kg−1, and maize at 81.8 g CO2eq∙kg−1. Primary sources of emissions included the fuel consumption of farming machinery, the production of fertilisers and pesticides, and soil emissions resulting from crop cultivation, which collectively accounted for 80–87% of total emissions, depending on the crop. The kind and amount of fertilisers used significantly influenced emissions. Furthermore, it was observed that lower crop yields were associated with elevated GHG emissions per unit of biomass produced.

Optimal nitrogen fertilizer rates combined with alternating wet and dry irrigation effectively reduce greenhouse gas emissions in rice-wheat rotation system under climate change scenarios.

The global agricultural sector accounts for ~14% of the total anthropogenic greenhouse gas (GHG) emissions, of which 46% are generated as N 2 O emissions from nitrogen fertilizers, 45% is contributed by CH 4 from manure and livestock fermentation, and 9% stems from CO 2 as a result of soil organic matter decomposition. Several mitigation strategies were proposed, with the aim to reduce GHG emissions. However, these practices are generally not evaluated in combination with adaptation strategies that farmers may implement independently to offset climate change impacts. The biogeochemical model DNDC was used to assess the role of sustainable mitigation and adaptation strategies on the optimization on crop yield and GHG emissions (CO 2 eq/ha) in an intensively managed agricultural region of Tuscany, Italy, under a predicted warmer and drier climate. The simulated crop was maize (Zea mays L.). The model was used to simulate maize yield using different mitigation strategies (type and amount of soil amendments) and adaptation strategies (sowing dates and maize cultivars). The future climate scenario was created by increasing present (1976-2005) air mean temperature by 2 °C and reducing daily rainfall by 10%. Results from the simulation suggested that longer growing season cultivars and earlier sowing dates in association with high N inputs may be adopted as strategies to increase maize yield compared with the standard crop and soil management strategy. Low N inputs with higher residue incorporation may be adopted to mitigate GHG emissions. However, in order to optimize both maize crop yield and GHG emissions only a few strategies were acceptable and included low organic N input with high residue incorporation in conjunction with a longer growing season cultivar and an early sowing date.

Greenhouse gas (GHG) emissions from agricultural soils can accelerate climate change, therefore, different soil fertilization techniques should be assessed before application to reduce GHG emissions. Pig slurry applications can greatly influence soil carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) emissions of arable fields; thus, it is important to find site-specific techniques to lessen any negative environmental impacts. In this study, we examined the short-term effect of pig slurry application techniques of spreading and injection on soil greenhouse gas and NH3 emissions under different irrigation amounts. We used the dynamic chamber method with in-situ gas analyzers. Our study showed that there were elevated emissions during the first week after slurry application; however, the difference between GHG emissions of spreading and injection treatments were not significant. Elevated GHG emissions (213–338% and 250–594% in the case of CO2 and N2O emissions, respectively) were observed under dry circumstances compared to irrigated treatments, as well as significantly higher NH3 emissions occurred for surface spreading under non-irrigated (dry) circumstances compared to other treatments. There were no statistically significant differences between the soil chemistry of different application techniques. However, pig slurry increased the available nitrogen forms (ammonium- and nitrate-nitrogen), which caused N2O and NH3 peaks regardless of treatment type. Leachate chemistry was more affected by irrigation strategies than application techniques. Our study highlights the importance of soil conditions at the time of application, rather than the application technique for fertilization using pig slurry.

Anaerobic digestion (AD) of livestock manure is better known for the economic advantage derived from biogas for energy rather than for its environmental benefits. Demonstration of relevant environmental benefits from AD of manure would thus enhance adoption of this technology on animal feeding operations (AFOs). The effect of AD of dairy manure on the emissions of ammonia (NH3) and greenhouse gases (GHG) during manure storage and also in subsequent land applications are presented in this paper. Measurements of GHG emissions from both AD and non-AD manure storages were made using a floating chamber and a photoacoustic gas analyzer (INNOVA model 1412). Emissions of GHG were determined using the standard closed chamber method from field plots applied with AD and non-AD manure. Data obtained indicate significantly higher fluxes of GHG (CO2, N2O, and CH4) from land applied with non-AD manure than from land applied with AD manure. In addition, injection of non-AD manure seemed to further increase CH4 flux from the soil. More than 50% emissions of CO2 and CH4 were observed during the first 3 days after manure was land applied. Emissions of GHG from the anaerobic lagoon holding AD manure, during all four seasons, were significantly lower than from the anaerobic lagoon with non-AD manure. In contrast, the reverse was observed with NH3 emissions. This data demonstrate some environmental benefits for AD of dairy manure prior to its storage and field application but also some potential increased emission of NH3 during storage.

Core Ideas The year × timing interaction affects cumulative N 2 O emissions. Injection of manure produces the highest cumulative N 2 O emissions. Injection of manure produces the highest corn yields. Manure application to agricultural soils enhances N 2 O emissions, but these emissions could be reduced by using improved application methods at the right time. We conducted a 3‐yr study on corn ( Zea mays L.) grown in Elora, ON, Canada, to test the effects of timing and method of liquid dairy manure application on year‐round N 2 O emissions. A randomized complete block design was set up every year evaluating two application times (fall vs. spring) and three methods of manure application (surface broadcasting, incorporation, and injection). Lower cumulative N 2 O emissions for fall than spring application (mean ± standard error = 1.2 ± 0.3 vs. 2.9 ± 0.3 kg N 2 O‐N ha −1 ) were found during the driest year (2012), whereas no differences in emissions occurred between application timing in near‐normal precipitation years (2013 and 2014). Nitrous oxide emissions were not affected by the timing × method of application interaction. Injected manure resulted in cumulative N 2 O emissions not different than surface broadcast manure (3.6 ± 0.5 vs. 3.0 ± 0.5 kg N 2 O‐N ha −1 ) but significantly higher than incorporated manure (2.2 ± 0.3 kg N 2 O‐N ha −1 ). Injection resulted in greater corn yields than the other two methods. Our results suggest that (i) method of application affects N 2 O emissions independently of timing; (ii) including N 2 O emissions for the non‐growing season avoided biased estimates for the fall application timing since 20 to 60% of total emissions occurred during this period; and (iii) incorporating manure is the best practice to mitigate N 2 O emissions, although if N rates are optimized, injection could potentially produce yields with low N 2 O intensity.

Core Ideas Manure storage and injection strategies were simulated using the Integrated Farming Systems Model. Strategies were verified using field data. We compared manure storage in environmental and economic model outputs. Introducing 6 mo of storage on a PA dairy farm decreased whole‐farm NUE without manure injection. Manure injection and 6 mo of storage gave the best combination of profit and environmental outcome. Application of livestock manure to farm soils represents a priority nutrient management concern in the Chesapeake Bay watershed. Historically, strong emphasis has been placed on adding manure storage to dairy operations, with the recognition that manure application methods can be improved. The Integrated Farm System Model was used to simulate manure management on a typical Pennsylvania dairy farm (100 milking cows, 80 ha). Converting the operation from daily haul to 6 mo of storage with broadcast application did not substantially change nitrogen (N) losses to the environment. However, switching to manure injection conserved ammonium N and improved manure N use efficiency by crops, even though it increased N leaching by 27% with 6‐mo storage and 13% with 12‐mo storage. Increasing manure storage from 6 to 12 mo with manure injection reduced nitrate N leaching by 38%, due to better timing of manure application to crop growth, but lowered annual net returns. Overall, manure injection and 6 mo of storage resulted in the best combination of profit and environmental outcome.