Do Tillage, Cover Crops, and Compost Management within Organic Grain Cropping Affect Greenhouse Gas Emissions?

Abstract

Core Ideas Drought decreased the CO2 and N2O 2 out of 3 yr of the study but in a normal precipitation year, GHG emissions increased significantly for corn and wheat but stayed relatively low for soybean. Increasing compost from 1× to 1.5× the recommended rate showed no increase in N2O emissions. NTCC and 1×+ compost rates typically resulted in the greatest GWP. Organic crop production is increasing with consumer demand, but research is needed on the best management practices that minimize greenhouse gas (GHG) emissions. This study was conducted in central Missouri from 2012 to 2014 using a 3‐yr rotation, consisting of corn (Zea mays L.), cereal rye cover crop (Secale cereale L.), soybean (Glycine max L.), winter wheat (Triticum aestivum L.), summer cover crop mix [Buckwheat (Fagopyrum esculentum Moench), sunn hemp (Crotalaria juncea L.), cowpea (Vigna unguiculata (L.) Walp.)], and cereal rye/hairy vetch cover crop mix (Vicia villosa L.). Treatments included tillage/cover crop practice (TCCP) combinations: (i) tillage with no cover crop (TNCC), (ii) tillage with cover crop (TCC), and (iii) no‐till with cover crop (NTCC) and compost additions relative to the recommended rate (0×, 1×, 1.5×). Carbon dioxide (CO2) and nitrous oxide (N2O) emission measurements followed GRACEnet protocol. GHG emissions were not influenced by management practices in 2012 due to severe drought. TCCP had direct (2013 corn, 2014 soybean) or interactive (2014 wheat) effects on CO2 emissions; compost had a direct effect (2014 corn) on N2O emissions. Drought in 2012 and 2013 contributed to generally low CO2 and N2O emissions (99–2924 kg CO2–C ha−1 and 0–0.8 kg N2O–N ha−1, respectively) while emissions increased in 2014 (527–7740 kg CO2–C ha−1 and <0.1–10.1 kg N2O–N ha−1, respectively). Across all years and crops, NTCC showed greater CO2 emissions than TNCC (1579 and 893 kg CO2–C ha−1, respectively). While few treatment differences were observed, TCCP resulted in more GHG emission differences than compost rate.

Linking Soil Health to Sustainable Crop Production: Dairy Compost Effects on Soil Properties and Sorghum Biomass

“…Compost is more beneficial than inorganic fertilizers from a sustainable agriculture perspective [11,13] because chemical fertilizers can have negative impacts on the environment [14]. However, the practice of using compost based on the N content may create an imbalance in plant nutrient availability [10,15]. Compost also contains organically bound N, phosphorus (P), potassium (K), calcium (Ca), and micronutrients, which support crop production through their effects on various physical and chemical processes in the soil [7,10].…”

“…The rate of compost application varies from farmer to farmer, but in general, the rate is determined with its N content [7], which depends upon the feed type, bedding materials, confinement time, and the duration of composting [11]. The high rate of compost application often supports crop production by improving soil health and nutrient availability [15], but it can lead to salt accumulation and negatively affect root growth and biomass production. High salt concentration in soils decreases microbial population, affects soil structure, organic matter mineralization, and nutrient availability [16].…”

“…11, x FOR PEER REVIEW 9 of 13 increase SOC, total N, and other nutrients[18,28]. Boardman et al[15] found increased NO3 --N with increasing compost rates. In our study, SOC and total N increased, but labile SOC and N fractions did not increase significantly with compost application rate.…”

Greenhouse gas emissions under winter wheat‐based organic and conventional crop productions

“…yield and quality, is getting increasingly popular (Boardman et al, 2018). Organic farming can provide ecosystem services similar to or better than conventional farming where chemical fertilizers, herbicides, and pesticides are used for crop production (Cavigelli et al, 2013).…”

“…Organic crop production can emit greenhouse gas (GHG) differently than conventional crop production. Boardman et al (2018) found that increased rate of compost application in organic farming increased N 2 O emissions. Hurisso et al (2016) reported that CO 2 and N 2 O emissions were lower in the organic than the conventional farming system under winter wheat (Triticum aestivum L.), but emissions were greater in the conventional than the organic system under fallow.…”