Agronomic and Environmental Performances of On-Farm Compost Production and Application in an Organic Vegetable Rotation

Nitrogen is crucial for the productivity of agricultural systems, although there is a growing demand for alternative cultural practices that reduce the off-farm inputs of this fertilizer. Cover crops provide a suite of services; among these, they can affect soil nitrogen content. In addition, the use of manure can contribute to a decrease in nitrogen loads from external inputs. The aim of this study was to evaluate, in processing tomato grown under an organic system, the combined use of cover crops (i.e., Vicia faba var. minor, Triticum aestivum, and Raphanus sativus) or cattle manure, with reduced rates of commercial nitrogen fertilizers. The yield and some important qualitative characteristics of the tomato fruits were considered. V. faba was able to enhance the effects of the external input of nitrogen with respect to the yield. External inputs increased tocopherol content with respect to the control but only when it was integrated with manure. The content of carotenoids was not affected by commercial fertilizer alone; however, when it was supplied in addition to cattle manure or incorporation of R. sativus, a decrease in β-carotene was observed. Moreover, lycopene also decreased when T. aestivum or R. sativus were used as cover crops. We conclude that the sowing of nitrogen-fixing cover crops or the use of manure are good strategies for combining internal and external inputs for the sustainable production of processing tomato.

Core Ideas Manure applied soil had higher CO2 and CH4 and lower N2O and NH3 emissions than urea. Beef manure with and without straw bedding produced similar yields and emissions. Soil inorganic N availability showed positive correlations to N2O and NH3 emissions. Manure and urea application produced similar corn yields. Land application of beef cattle (Bos taurus) manure can improve soil health and increase corn (Zea mays L.) yield compared with commercial fertilizers. However, ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions may lead to nutrient losses and environmental concerns. The objective of this research was to quantify NH3, N2O, CO2, and CH4 emissions from commercial and manure fertilizers applied to corn. In addition, residual soil N, corn yield, plant tissue N, and grain N were determined. The 2‐yr field study was conducted in Fargo‐Ryan silty clay soil. Treatments consisted of urea only (UO), solid beef manure (SM), solid beef manure with straw bedding (BM), and no fertilizer (NF). All treatments were applied to meet the corn N demand and yield goal of 10,760 kg ha–1 (160 bu ac–1). Greenhouse gases were quantified using static flux chambers, and NH3 was quantified using acid traps, for a total of 13 measurement dates in each growing season. Manure applied to soil reduced cumulative N2O by 23% in SM and 31% in BM compared with the UO soil. Cumulative CO2 emission (cCO2) was 42% lower in UO than in SM or BM. Cumulative CH4 emission (cCH4) ranged from –0.04 (NF) to 0.21 (BM) kg CH4–C ha–1, with the highest emission from BM. Cumulative NH3 emission (cNH3) was 11% lower in manure than UO. Cumulative residual soil N was 11% greater in Year 2. Fertilizer source did not affect the yield and grain N uptake (P > 0.05). The results highlight the challenges that come with variability in manure, soil, and weather as well as the potential for meeting crop N demand while reducing greenhouse gas emissions when using manure as an N source.

Two field experiments were conducted to evaluate the effects of comparable rates of swine lagoon effluent and commercial fertilizer at different harvest dates on dry matter yield and nutritive value of bermudagrass (Cynodon dactylon L.) grown on an acid Vaiden silty clay (very fine, montmorillonitic, thermic, Vertic Hapludalf) and johnsongrass (Sorghum halepense L.) grown on an alkaline Okolona silty clay (fine, montmorillonitic, therimic, Typic Chromudert). At each site, a randomized complete block design with a factorial arrangement of treatments replicated four times was used. Treatments were multiple effluent irrigations resulting in four N rates from 0 to 665 kg N ha−1 yr−1. In each block, commercial fertilizer (N, P, and K) treatments were applied to additional plots at rates equivalent to swine effluent rates. Total dry matter yield and crude protein (CP) for bermudagrass and johnsongrass reached a plateau with application of approximately 450 kg N ha−1 from either swine effluent or commercial fertilizer. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) peaked at the low fertilization rate and then declined with increasing effluent and commercial fertilizer rates. An inverse relationship was obtained for in vitro true digestibility (IVTD) in response to fertilization rate for both grasses. Forage dry matter, CP, NDF, and ADF levels peaked in the July harvest and then declined, but forage IVTD level declined in July harvest. Only in July 1996, forage NO3–N concentration was lower for swine effluent than commercial fertilizer. Swine effluent and commercial fertilizer had similar effects on forage dry matter yield and nutritive value.

Recycling agricultural residues to obtain production factors directly in the farm could be crucial to improve sustainability. The aim of this study was to use plant residues to produce both organic amendments (on-farm compost) and plant biostimulants (liquid extracts). They were applied on a 2-year organic fennel crop, both alone (compost on-farm – OC) and combined (compost on-farm plus parsley extract – OCex) and compared with two commercial organic fertilizers (of vegetal origin – ORG-V; and of animal origin – ORG-A) and an unfertilized control, alone (NF) and combined with the extract (NFex). On average, the agronomic performance of compost treatments was higher than the unfertilized control and comparable to ORG-V. The use of the plant extract induced a synergistic effect with the on-farm compost, likely due to the P, K, Ca, Fe, and Mg supplementation by the extract to fennel crop. This is a relevant result, particularly in the perspective of widening the number of fertilizers produced inside the farm in organic farming, thus avoiding both synthetic fertilizers and commercial organic fertilizers. Finally, on-farm compost use reduced GWP emissions, since an average value of −12.44%, compared to the commercial fertilized treatments, was found, thus suggesting environmental sustainability.

Surface runoff water quality from a rescue pasture receiving surface application of organic wastes and commercial fertilizer was evaluated at Clemson University (Clemson, S.C.). Dairy manure, poultry manure, and municipal sludge were the organic wastes used in this experiment. Ammonium nitrate was the commercial fertilizer. The organic wastes and commercial fertilizer were applied at the rate of 112 kg N ha−1 to eight plots during four different periods. Due to an extremely dry year, runoff events were produced by irrigation. The runoff water was collected and samples were analyzed for pH, total P, total suspended solids, total Kjeldahl N, NH4‐N, NO3‐N, and chemical oxygen demand.The nutrient concentrations in surface runoff were more dependent on the number of rainfalls since application of the fertilizer than on the quantity of rainfall or runoff. The concentrations of potential pollutants from surface‐applied organic wastes or commercial fertilizer were reduced by between 80 and 55% after two runoff events. The NO3‐N concentration in the surface runoff from the plots receiving the commercial fertilizer exceeded the permissible public water supply standard during the first runoff event. The overall nutrient loss in the runoff was found to be minimal (< 4% of total Kjeldahl N and chemical oxygen demand and < 2.5% of total P).

<b><sc>Abstract.</sc></b> A two-year study was conducted to quantify ammonia (NH₃) and greenhouse gas (GHG) emissions following land application of manure and commercial fertilizer to corn fields. Four treatments were evaluated: commercial fertilizer (CF), solid beef manure (SM), solid beef manure with corn stover bedding (BM), and no fertilizer (NF). The CF, SM, and BM treatments were applied in the fall to meet corn N demand. Air samples were measured following land application and at two-week intervals from planting to harvest. Sixteen plots were used with four replications per treatment. Average daily NH₃ flux were greater from plots that received the CF treatment (2436 µg m^-2 hr^-1) compared to plots that that had NF (1875 µg m^-2 hr^-1), SM (1857 µg m^-2 hr^-1) and BM (1850 µg m^-2 hr^-1) treatments applied. No differences were detected in daily CH₄, CO₂, or N₂O flux due to fertilizer treatment, but all gases measured varied significantly between growing seasons. Cumulative NH₃ emissions were higher for CF plots (214.3 kg ha^-1) than SM (147.6 kg ha^-1), BM (148.8 kg ha^-1), and NF (151.5 kg ha^-1). Cumulative CO₂ emissions were higher for SM (5.3 Mg ha^-1) and BM (4.9 Mg ha^-1) plots compared to CF (2.6 Mg ha^-1) and NF (2.5 Mg ha^-1) treated plots. The significant differences between emissions from year to year emphasizes the need for long-term studies to better understand gaseous emissions from fertilizer application. With similar emissions from all fertilizer treatments, producers can consider using manure as a nitrogen source to reduce costs associated with purchasing commercial fertilizer.

105 Botanical composition, yield, horse preference, and forage and soil nutrient values of grass pastures treated with different soil amendments

Long-term cover crops and no-tillage in Entisol increase enzyme activity and carbon stock and enable the system fertilization in southern Brazil

Soil management with the use of lime and agricultural gypsum can influence the development and yield of cotton and soybean crops. The use of cover crops avoids soil degradation and ensures nutrient cycling on the soil surface. In most cultivated species, the application of lime and agricultural gypsum provides corrections in the sub-surface soil, keeping the nutrients available. This study aimed to (i) verify whether cotton and soybean cultivated in succession to cover crops affect its agronomic performance and (ii) evaluate the influence of lime and gypsum doses on the agronomic performance of these crops. Two experiments were performed. The first experiment consisted of cotton cultivated in the off-season, and the second, of soybean cultivated in the regular season. The experiment was carried out under three plant residues (Urochloa ruziziensis, Pennisetum glaucum, and fallow area), combined with lime and gypsum doses. The experiment consisted of a completely randomized block design with four replications. For the cotton crop, only the gypsum doses influenced the variables plant height, initial and final population, and yield. Cover crops did not influence the agronomic performance of cotton and soybeans. The increase of lime doses resulted in a linear increase in cotton and soybean yield. The highest gympsum dose improved the agronomic performance of cotton plants; however, it only influenced the height of soybean plants.

A 2-year field trial was carried out in a climate change context on organic tomato crop. The objectives were: (1) to study the best synergistic combination of a set of agro-ecological techniques, as potential adaptation strategies in Mediterranean environment [i.e.: soil surface shaping; crop rotations; cover crops introduction (barley, vetch and their mixture); cover crop termination techniques (roller crimper—RC vs green manure—GM) and organic fertilization]; (2) to evaluate the sustainability of these techniques by assessing energetic performance. In both years, the barley-RC and mixture-RC combinations reduced weeds fresh and dry weights. In 2014, the combination of commercial organic fertilizer and vetch gave both the highest tomato marketable and total yields (26.88 and 31.97 t ha−1, respectively). In 2015, these production parameters decreased by 30.7 and 35.4%, respectively compared to 2014, and GM-cover crop produced on average more than twice as much as RC-cover crop. The cover crop termination by RC reduced soil mineral N peak than GM treatment, at full flowering in particular in plots after vetch and in the mixture plots in 2014 and 2015 respectively, thus reducing the potential environmental impact by nitrate leaching. The highest energy consuming input was fertilizers (by 57%). The highest energy efficiency and net energy were found in the vetch-GM combination (with low fertilizer input). The research points out that agronomic practices must be fine-tuned to the specific pedoclimatic condition for an efficient use of energy. Moreover, agronomic input reduction is not only feasible, but also creates environmental benefits.

Mixed Solid Municipal Waste-Based Biochar for Soil Fertility and Greenhouse Gas Mitigation

Recently, landfill mining (LFM) has emerged as a promising strategy for addressing the challenges of waste management, resource recovery, and climate change mitigation. This work explores the potential of landfill mining to transform traditional landfills from environmental liabilities into assets. By recovering nutrients, energy, and materials from landfill leachate, landfill mining can reduce greenhouse gas (GHG) emissions, particularly methane (CH 4 ), while contributing to the circular economy. This study evaluates the technologies applied in landfill mining, such as bioreactors, anaerobic digestion, and leachate recirculation, based on published literature from 2000 to 2025, focusing on their value in resource recovery. More specifically, this study aims at recovering renewable CH 4 energy from leachate and extracting macro-nutrients such as nitrogen (N), phosphorus (P), and potassium (K) which can be turned into commercial fertilizers. This study further analyzes the advantages of landfill mining, which include reducing CH 4 emissions by up to 30% and the potential energy value of 15 GWh from 1.5 million m 3 of CH 4 . The study also explores the socio-economic consequences of landfill mining, focusing on employment opportunities, improved waste management systems, and enhanced local community welfare. Additionally, this work discusses the technological, financial, and regulatory challenges that hinder the widespread adoption of landfill mining for promoting circular economy. Finally, this work calls for further investment, research, and policy development to unlock the full potential of landfill mining as a sustainable waste management strategy and a key contributor to resource recovery in the circular economy paradigm.

Effects of biochar produced from distiller grains on agronomic performances of sorghum (Sorghum bicolor L.) and greenhouse gas emissions from soil

Effects of cover crops on soil CO2 and N2O emissions across topographically diverse agricultural landscapes in corn-soybean-wheat organic transition

Management of the Parthenium hysterophorus through biochar formation and its application to rice-wheat cultivation in Pakistan