Compost Rates Research Articles

Effects of food waste and green waste composts on yield and nitrogen‐use efficiency in irrigated tomato crops

AbstractComposts are increasingly used to enhance soil health and agricultural sustainability, but their impacts on nitrogen (N) availability are unclear. In a 3‐year field experiment with subsurface drip‐irrigated tomatoes (Solanum lycopersicum), we investigated the effects of food waste and green waste co‐compost (FW) and green waste compost (GW) on yield, nitrogen‐use efficiency (NUE), nitrate leaching potential, and fertilizer N retention. Various combinations of compost rates (0, 9, or 18 t ha−1) and fertilizer N levels (0%, 70%, 85%, and 100% of the recommended rate) were examined, and 15N‐labeled fertilizer was used. In Years 2 and 3, FW and GW either maintained or increased crop yield compared to no compost when 0% or 70% N was applied; however, lower NUE was observed in the compost treatments compared to no compost when 70% or 85% N was supplied. Postharvest, FW showed greater fertilizer N retention in topsoil than GW and controls, while no difference in nitrate leaching potential was found among treatments, except for Year 2 during which FW exhibited the lowest potential. These results suggest that compost can immobilize fertilizer N, reducing its uptake by crops but enhancing soil retention, potentially acting as an N source or a primer of soil N mineralization. Future research is needed to assess compost's impact on N gaseous emissions and distinguish its dual roles as an N source and a soil N mineralization primer. This is essential for developing nutrient management guidelines to minimize N losses.

Influence of Different Rates of Plant-Based Compost on Clay Soil Metal Behavior and Human Health Risk Assessment in Moringa oleifera Leaf Biomass

An investigation of the impact of adding plant-based organic compost to clay soil from a Moringa oleifera farm focusing on the metal content, bioavailability, and accumulation of nutrients in M. oleifera leaves was conducted. Clay soil was mixed with 15%, 30%, 45% and 60% plant-based organic compost (by volume) in 20 cm wide, 2 L pots. Moringa oleifera plants were planted in four replicates of each treatment and control group. Results revealed that the addition of compost significantly (P < 0.05) altered the concentration of metals in the soil. Correspondingly, accumulation of nutrients in M. oleifera leaves increased with the addition of compost to the soil, except for cobalt and chromium. Trace elements had minimal bioavailability in the amended soils, and their presence in the leaves was lower than the permissible trace metal levels in food. The 30% combination had the highest concentration of calcium (45 042.5 mg/kg), magnesium (17430.0 mg/kg) and phosphorous (8802. 5 mg/kg) in M. oleifera leaves. The study concluded the addition of compost improved bioavailability of nutrients in the soil and their concentration in M. oleifera leaves. The target hazard quotients for heavy metals was less than one, indicating that M. oleifera leaf biomass harvested from soil amended with plant-based compost is safe for human consumption. These results serve as guidelines for recommended organic certification requiremets where plant-based compost is often used in the fast-growing herbal industry.

Investigating the Effects of Various Soil Amendments on Forages Production in the Field

An initial investigation into the utilization of recycled plant and animal residues as soil amendments (SAs), including compost, biochar, and soil conditioner, was conducted using alfalfa crops. This study evaluated the impact of SAs on alfalfa seed germination, resulting in an 87% germination rate for biochar, 82% for soil conditioner, and 82% for compost. In comparison, untreated seeds displayed a 78% germination rate. After successful germination, the SAs were employed to enhance soil health, with a focus on water conservation and increased forage yield. The study used sandy-textured soil with moderate alkalinity, very slight salinity, slight calcareousness, and high permeability. The germination trial confirmed that SAs usage did not hinder seed germination, even for salt-sensitive crops like alfalfa. Two field experiments were carried out in Al-Wafra, using different application rates of compost, biochar, and soil conditioner at 5, 7.5, and 10 tons per hectare. The results highlighted the positive impact of SAs application on increasing forage production, with varying degrees of enhancement, and confirmed a 40% reduction in water usage compared to treatment without SAs but under 100% irrigation (100% ETc). In conclusion, SAs show promising potential for local forages intensification and water conservation.

Exploring the impact of circular economy practices on ecological footprint, inflation rate, and renewable energy consumption: evidence from G20 economies.

The circular economy (CE) has acquired significant interest for its potential to contribute to sustainable development (SD). The present study utilizes empirical methodology, specifically panel data analysis, to examine the distinct effects and outcomes of the circular economy and its associated factors within a unified framework. The focus is on the G20 countries from 2008 to 2021. We evaluated the influence of various CE value sources (renewable energy consumption, composting rate, repair services availability, recycling rate) and a factor-analysis-derived measure of the CE on economic, environmental, and social aspects of SD. The objective was to assess the distinct effects and outcomes of CE and its components in a unified framework-the analysis utilized panel data from G20 countries from 2008 to 2021. Our findings show a substantial influence of CE in achieving SD, with positive implications for the economy, environment, and society. However, the impact of each CE value source on the SD dimensions shows variation. While renewable energy consumption (RENEC) and composting rate (CR) lessen environmental impact, recycling rate (RR) shows no significant effect, and repair services availability (RSA) increases the Ecological Footprint (EFP). Notably, RSA is the sole CE component, showing a positive economic impact at the national level. Additionally, RENEC, RSA, and RR contribute to reducing the inflation rate (INFR). Policymakers should undertake detailed impact assessments to develop effective, tailored strategies based on each country's unique goals. The findings of this study have important policy implications, particularly in terms of emphasizing targeted strategies for implementing CE practices to achieve sustainable development.

Mitigation of water stress by compost and arginine application and its impacts on barley production

BackgroundWater-scarce locations necessitate the deployment of creative and sustainable techniques for managing water for agricultural production. Field experiment was conducted at the Experimental Research Farm of National Research Centre, Nubaria region, Egypt to alleviate the harmful effect of water stress on the yield of Mediterranean barley varieties (Giza 125, Tombari, Ksar Megrine and Tamellat) by compost (0.0, 2.0, 4.0, 6.0-ton fed−1) and arginine application (0.00 and 1000 ppm) under deficit irrigation. The amounts of irrigation water applied were “900 and 450” m3 fed−1 to sufficient irrigation and deficit irrigation, respectively.ResultsThe greatest and most significant values of the chlorophyll values and relative water content values obtained at the treatment supplied with 6.0-ton compost fed−1 and sprayed with Arginine. There was a significant dramatic decrease in proline content with increasing compost application rates and treated barley plants by Arginine for all the studied barley varieties under both studied irrigation treatments. Increasing compost application rate is associated with significant increase in number of spike m−2 without or with arginine. Barley Tombari variety received 6.0-ton compost fed−1 gained changes to give a greatest significant value of grain (ton fed−1) under sufficient irrigation and Tamellat under deficit irrigation situation. The significant maximum values of the grain yield (1.96- and 2.09-ton fed−1) were attained at Tombari and Tamellat varieties which received 6.0-ton fed−1 compost with or without arginine under sufficient irrigation. The increases in compost rate increment changes to incremented grain yield values with arginine application more than untreated one. The greatest and significant grain yield was found at the treatment received 6.0-ton compost fed−1 with arginine foliar application.ConclusionCompost application has an important role in maintaining greatest water use efficiency for plant and arginine application reported to contribute in reduction in destructive effects of a biotic stress thus their importance in increasing the barley production under water stress.

Comparative efficacy of wheat-straw biochar and chicken-waste compost on cadmium contaminated soil remediation, reducing cadmium bioavailability and enhancing wheat performance under cadmium stress

Cadmium (Cd) pollution of soil and food crops is a widespread environmental issue caused by excessive industrialization, unsustainable urbanization, and intensive farming practices. Cd, a hazardous element, poses significant risks to agro-environmental sustainability, food safety, and human health. Using organic materials such as biochar and compost to stabilize Cd in contaminated soil is an environmentally benign and cost-effective strategy for remediating moderately to highly polluted soil. However, in response to the scarcity of comparative studies on biochar and compost efficacy, this research explores the impact of wheat-straw biochar and chicken waste compost on Cd-contaminated soil remediation. A greenhouse experiment using two application rates (1.5 % and 2.5 %) of biochar and compost in 10 mg kg−1 Cd-contaminated soil revealed significant (p≤0.05) effects. The 2.5 % compost application increased soil organic carbon (SOC) from 0.45 % to 0.85 %, while 2.5 % biochar enhanced soil pH from 7.1 to 7.7 and electrical conductivity (EC) from 0.33 to 0.44 dSm−1. Notably, 2.5 % biochar significantly reduced Cd bioavailability from 9.49 to 4.90 mg kg−1, root accumulation from 29.8 to 16.4 mg kg−1 and shoot translocation from 16.8 to 8.4 mg kg−1. This reduction was confirmed through translocation factor (51.5 %) and immobilization efficiency (48.4 %). Furthermore, 2.5 % biochar improved chlorophyll content (a, b, and total) and wheat morphological attributes under Cd stress in soil. Overall, higher rates of biochar (2.5 %) and compost (2.5 %) effectively mitigate Cd uptake, improve soil properties, and enhance physiological and morphological responses, suggesting their promise for sustainable soil management practices.

Growth and Yield Response of Carrot (Daucus carota L.) to different Soil Amendments

Carrot (Daucus carota L.) is an important vegetable that is ranked tenth among the succulent vegetables in the world. It is easy to cultivate and requires a moderate amount of nutrients in comparison to other vegetables. However, carrot production in Liberia is almost negligible, as farmers are not aware of its requirements, its cultivation, and the unsuitable environmental conditions. The objective of this study was to assess the growth and yield performance of carrot under different soil amendments. The experiment was done at the Cuttington University research and demonstration site in a randomized complete block design (RCBD) with three replications. The treatments were: 10 t ha-1, 15 t ha-1, and 20 t ha-1 compost; 300 t ha-1 NPK (15:15:15); and control (0 t ha-1). The distance between plots and between blocks was 0.5 m and 1 m, respectively. Results indicated that The highest recorded plant root length (11.10 cm) occurred in the 20 t ha-1 compost application, while the lowest (6.84 cm) was observed in the control treatment. The highest root diameter (22.89 mm) was recorded in the treatment with 20 t ha-1 while the lowest (17.59 mm) was recorded in the control treatment. Results showed that the maximum root weight (31.73 g) occurred in the 20 t ha-1 compost treatment, while the minimum (12.33 g) was observed in the control. These variations are likely attributed to nutrient levels, which play a vital role in promoting root length, diameter, and overall yield in the plant. That means the lowest values in all the parameters might be due to the low rate of compost applied to the soil. In conclusion, the highest overall growth and yield performance among carrot plants were observed in the 20 t ha-1 compost treatment, followed by 15 t ha-1, 300 t ha-1 NPK (15:15:15), 10 t ha-1, and the control. It is therefore recommended that farmers apply 20 t ha-1 of compost for maximum growth and yield performance in carrot production.

Compost Amendment Enhances Leaf Gas Exchange, Growth, and Yield in Water-challenged ‘Crimson Giant’ Red Radish (Raphanus sativus L.)

Red radish is a nutritious root vegetable crop that has a short production cycle. Water deficit limits plant productivity, affecting its quantity and quality. Compost amendment offers a potential solution to mitigate water deficit effects. This study assessed the impact of compost manure rates (0%, 50%, 75%, and 100%) and irrigation treatments (40%, 60%, 80%, and 100% of evapotranspiration) on ‘Crimson Giant’ red radish production. Significant differences in growth and quality were observed among these treatments. Compost rates of 75% and 100% improved leaf gas exchange, plant growth (leaf count, fresh weight, dry weight, and area; stem length), root development, total yield (root fresh weight, dry weight, diameter, and length), and root quality (vitamin C and total soluble solid and titratable acidity). The 100% compost and 100% irrigation combination achieved the highest yields. Under water deficit, applying 75% or 100% compost with 80% irrigation conserved 20% of water while maintaining radish output. Overall, compost amendment effectively enhanced red radish growth and production under water deficit.

Comparative effect of different irrigation levels and soil amendments on cabbage productivity in semi‐arid Central Namibia

AbstractIn semi‐arid Central Namibia, poor sandy soils limit sustainable crop production. We assessed cabbage performance in two split‐plot field experiments. In Experiment 1, treatments comprised two irrigation levels: full irrigation (watered 3 days a week) and reduced irrigation (watered 2 days a week) as the main plot factor and six soil amendments (biochar; compost; zeolite; nitrogen, phosphorus potassium [NPK]; Be‐Grow boost [L] hydrogel; and hoof and horn + bone [HHB] meal) as subplot factors in three replications. Full irrigation produced a significantly higher yield (21.1 t ha−1), head weight (0.958 kg) and larger head girths (42.1 cm). Biochar produced the highest marketable heads (24,884 heads ha−1), water use efficiency (76.0 kg ha−1 mm−1) and the largest head girths (42.7 cm). In Experiment 2, water was applied 5 and 4 days a week for full and reduced irrigation; the application rates of compost, HHB meal, Be‐Grow boost (L) hydrogel and NPK were modified. The interaction of Be‐Grow boost (L) hydrogel, NPK and biochar with full irrigation and HHB meal with reduced irrigation produced more marketable heads (28,935, 28,009, 27,546 and 28,703 heads ha−1, respectively). Therefore, full irrigation with these amendments could be used for resilient cabbage production in Central Namibia.

The Effect of Compost Type, Application Rate, and Maturity on Nutrient Leaching and Soil Nutrient Levels

ABSTRACT The application of compost to agricultural soils can increase nutrient leaching, causing several environmental problems. Conversely, proper management of compost application can reduce environmental risks. Agronomical trials were conducted in greenhouses in Morocco to compare the effects of varying compost application rates, types, and maturity, as well as the number of growing days, on nutrient availability and nitrate leaching in a loamy sandy soil. Additionally, the study examined the impacts of these factors on soil physical and chemical characteristics. The compost used in this study was derived from a combination of two cost-effective materials, municipal waste, and poultry manure. Tomato plants were cultivated in pots amended with compost over a period of 65 days. The soils were treated with eight composts (plus a control) obtained from municipal solid waste (MSW) mixed with poultry manure (PM) at two ratios, 3:2 and 2:3 weight weight−1 (ww−1) (C1 and C2, respectively), used at two different ages (105 days and 173 days) and at two doses (32.5 g pot−1 and 65 g pot−1, equivalent to 40 Mg ha−1 and 80 Mg ha−1). Two simulated leaching events (the first after planting and the second at harvest) were performed. The concentration of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN) in leachate varied with the number of growing days and increased in the leachate of the non-amended soil after planting. At both sampling times, compost C1, aged 173 days (d), significantly decreased COD in the leachate compared to compost C1 aged 105 d. Compost increased nitrate leaching compared with the non-amended soil. Nitrogen leaching was primarily in the form of nitrate, ranging from 61% to 78% over the whole experimental period. Compost also decreased leachate concentrations of iron (Fe) and chromium (Cr), for other metals, such as cobalt (Co) and nickel (Ni), values were very low. Moreover, compost increased total organic carbon by up to twofold at both sampling times, with the most substantial increase observed with a dose of 65 g pot−1 of compost C2 (aged 105 days). Most compost treatments also increased available phosphorus (P), inorganic nitrogen (N), total nitrogen (TNK), cation exchange capacity (CEC), and electrical conductivity (EC) at both sampling times but had no effect on pH. The metal content in the soil exhibited a decrease compared to the control soil. Overall, our study suggests that nitrogen leaching can be reduced by optimizing compost rates, properties, and stability to synchronize with crop needs.

Responses of bacterial and archaeal communities to nitrogen fertilization in a compost-amended soil

The use of organic compost associated with nitrogen (N) fertilization has been intensively studied, revealing the promotion of changes in soil microbial properties. However, few studies have reported the effect of N application in soil amended with organic compost in the long-term on soil microbial communities. This study assessed the responses of bacterial and archaeal communities to N application in soil with a long-term amendment of organic compost obtained from tannery sludge. The application of high and low rates of compost increased the abundance of Actinobacteria and Thaumarchaeota, respectively, while the application of N did not change the relative abundance of bacterial and archaeal groups. The long-term application of compost promoted an increased abundance of specific bacterial groups, including Solirubrobacter, Microvirga, and Geodermatophilus. Regardless of the application of N, higher microbial complexity and interconnection were observed with the application of compost. This study showed a small effect of N fertilization on the microbial community, which suggests that N may not be a limiting factor for microorganisms in soil under long-term amendment of organic compost. Our findings showed that compost application has a stronger impact on soil microbial communities than N fertilization, and it could be useful in agricultural productivity.

Amended Crop Wastes Compost Affect Soil Chemical Properties and Yield of Maize (Zea mays L.) in Nigeria Savanna

Aims: To evaluate the efficacy of poultry droppings amended cocoa pod husk and rice mill wastes, as a substitute for costly inorganic fertilizers on some soil properties and yield of maize.&#x0D; Study Design: Experiment was laid in randomized complete block design.&#x0D; Place and Duration of Study: Two year field study was conducted at the Research Farm of the Cross River University of Technology during 2019 and 2020 cropping seasons.&#x0D; Methodology: Two compost types: cocoa pod husk and rice mill wastes both amended with poultry droppings at the ratio of 3:1 for cocoa pod husk + poultry droppings and rice mill waste + poultry droppings respectively. Each compost type was applied at rate of 2.5, 5.0, 7.5 and 10 t ha-1 with absolute control (0 t ha-1 compost) and optimal control NPK 20.10.10 at 300 kg ha-1 making a total of 10 treatments replicated three times. The effect of the amendments were assessed on soil pH, OM, N, P, exch. Ca, K, Mg, EA, ECEC and maize yield.&#x0D; Results: The compost rates increased soil pH, OM, N, P and the exch. K, Ca, EA, and ECEC over the pre-treatment soils and the controls. Cocoa pod compost amendments with poultry droppings at rate of 7.5 t ha-1 produced highest plant dry matter 8.21gplant-1 and 8.08 gplant-1 in 2019 and 2020 (P = .05) respectively and the highest grain yield of 3.92 t ha-1 and 3.89 t ha-1 respectively in 2019 and 2020. The least grain yield was in the absolute control, which yield was 0.38t ha‑1 and 0.42 t ha-1, respectively in 2019 and 2020.&#x0D; Conclusion: Amended cocoa pod husk compost is a suitable soil amendment for optimum yield of maize and improvement of soil chemical properties in the study area and a substitute for mineral fertilizers for resource poor farmers.

Compost-assisted revegetation of highly phytotoxic sulfidic tailings with Medicago sativa L. plants grown from the seed to seedpod stage under greenhouse experimental mesocosms conditions

The revegetation of highly phytotoxic sulfidic tailings is a challenging task which may often be successfully accomplished only following the addition of soil amendments. This study evaluated the use of green compost at increasing rates (10, 25 and 50% v/v) for the revegetation of extremely acidic sulfidic tailings of the North Mathiatis mine, Cyprus, with the use of alfalfa (Medicago sativa L.) plants, under greenhouse conditions. Alfalfa seeds were successfully germinated in tailings amended either with 25% or 50% (v/v) compost (52 and 85%, respectively). Plants managed to complete their life cycle and produce seeds only in the tailings amended with 50% (v/v) compost, since plants grown in tailings amended with lower rates of compost (i.e., 10 or 25% v/v) showed severe symptoms of phytotoxicity and eventually died. The amendment of tailings with 50% (v/v) green compost resulted in increased pH values, water holding capacity and organic content levels, soil respiration rates, as well as changes in soil elemental composition compared with tailings alone treatment, which in turn facilitated the growth and development of alfalfa plants during the whole experimental period (140 days). Plants managed to reach the late seedpod growth stage, indicating their potential regeneration and continual existence to the amended tailings, simultaneously uncovering the development of favorable conditions in the rhizosphere for the successful revegetation of studied tailings.

Effect of Chemical Nitrogen and Compost Rates on Wheat Productivity and Soil Properties at District Sriganganagar of Rajasthan

Two field experiments were conduct at the Experimental site with the help of agriculture research Centre Sriganganagar Rajasthan, during season 2020-2021and 2021-2022 to study the effect of chemical nitrogen rate (0, 30, 60 kg N/fed.) and compost rates application (0,1.5, 3 ton /fed.) and its interaction on productivity of the wheat Raj-3077 and soil properties. Treatments were arranged in split plot design with three replicates (the main plots included chemical nitrogen. while, compost rates were allocated at the sub plots). The results revealed that increasing chemical nitrogen rates from 0 to 60 kg N/fed. significantly increased plant dry weight/m2, plant height, number of tillers and spikes/m2, number of grains /spike, weight of 1000-grain, grain and straw yield/ fed. and grain protein content in both seasons. Application of 60 kg N/fed. recorded the highest values for all previous studied traits compared with untreated plants (control treatment) which gave the lowest values. compost rates recorded significant differences for all studied traits of wheat as plant dry weight/m2, leaf area index, plant height, number of tillers and spikes/m2, number of grains/spike, weight of 1000-grains, grain yield, straw yield and grain protein content in both seasons except for dry weight in the first season; The application of 3 t/fed. recorded the greatest significant values for all previous studied traits compared with the untreated control treatment which showed the lowest values. The interaction between chemical nitrogen and compost rates application had a significant effect on plant dry weight/m2, leaf area index, plant height, number of tillers and spikes/m2, number of grains /spike, weight of 1000-grains, grain and straw yield in both seasons, with exception of plant dry weight/m2 in the first season and the grain protein content in both seasons. Application of 60 kg N/fed. + 3 t compost /fed. gave the highest significant value of plant height, number of tillers and spikes/ m2, weight of 1000 grain and grain yield/fed. without significant differences between them. The highest significant values of grain yield in both seasons and straw yield in the second season were achieved by 60 kg N/fed. + 3 t compost /fed. followed by 30 kg N/fed. + 1.5 t compost /fed. Soil salinity (ECe) and saturation hydraulic conductivity (Ks) as well as available N, P, and K in the soil were significantly increased with increasing N rates applied generally up to 60 kg N/fed., while soil pH and bulk density (ρa) were not significantly affected in the two seasons. Saturation hydraulic conductivity (Ks) as well as available N, P, and K in the soil were significantly increased with increasing compost rate applied generally up to 3 ton/fed., while soil salinity, pH and bulk density were significantly decreased in the two seasons Finally, adding compost at rate of 3 t/fed. resulting in the improvement of soil properties. From the results and under the conditions of this study, it could be concluded that application of 60 kg N/fed. combined with compost at rate 3 t/fed producing the highest grain and straw yields.

Physiological responses of oregano under different water management and application of fermented bokashi compost

Growing conditions such as water supply and soil fertility influence oregano morphological development and physiological responses. Our study aimed to analyse the physiological responses of oregano plants grown under different water conditions and bokashi application rates. The experiment was carried out in a greenhouse under a randomized block design and a 3 x 4 factorial scheme. Treatments encompassed three water replacement levels (60, 80, and 100% crop evapotranspiration - ETc) and four bokashi rates (0, 100, 200, and 300 g m-2), with five replications each. Oregano seedlings were transplanted and grown in a spacing of 0.3 m between plants and 1 m between bed rows. After 60 days, treatments were evaluated for photosynthetic rate (A), stomatal conductance (Gs), internal CO2 rate (Ci), transpiration (E), and water-use efficiency (WUE). Data underwent variance analysis by F-teste, multivariate analysis, and Pearson's linear correlation. Oregano physiological responses were significantly influenced by water replacement level and the application rate of fermented bokashi compost. The multivariate analysis allowed us to analyse the interaction effect between water replacement level and bokashi rate on photosynthesis, stomatal conductance, internal CO2, and transpiration.

Determination of Lime Requirement with Compost on Acidic Ultisols for Wheat Crop in the Gurage Zone of Ethiopia

Acidic soil adversely affects the plant growth and production. Various ameliorating strategies are known, but the optimum rate of lime and compost rate determination for better nutrient management and production in acid Ultisols was not well studied, so the main objective of this study was to determine optimum lime and compost rate for wheat production. A pot experiment was performed on the soil collected from Yefereze (Cheha District). The incubation trail was conducted in factorial combination of four level lime (8.44, 6.33, 4.22, and 0 t·ha−1) and compost (15, 10, 5, and 0 t·ha−1). The sixteen treatments were arranged in completed randomized design (CRD) with triplicate replications in the greenhouse. After 75 days, each pot that was planted with wheat and crop performance had been monitored. The textural class of the soils of the experiment was clay with strongly acidic pH. The organic carbon (2.17%) and total nitrogen content (0.17%) status was medium. The available phosphorus (Av. P) contents were very low (1.63 ppm). The experimental study result revealed that all the three rates of lime and compost continuously improve the soil pH throughout the study periods and the maximum soil pH (6.53) was obtained in combination of 8.44 t·ha−1 and 10 t·ha−1 lime and compost, respectively. The compost amended treatment indicated slight improvement in soil reaction which assert that using compost alone did not reduce soil acidity within 75-day periods in strongly acidic soil condition for suitable wheat production. Liming alone or integrated application increases soil pH (4.69 to 6.53), cation exchangeable capacity (CEC) (27.18 to 31.58 cmolckg−1), exchangeable calcium (3.56 to 8.43 cmolckg−1), available phosphorus (Av.P) (1.63 to 5.27 ppm), total nitrogen (TN) (0.19 to 0.24 ppm), and exchangeable acidity reduced (0.73 cmolckg−1 to trace). Integrated application of 8.44 and 5 t·ha−1 lime and compost rates improve the overall soil property and maximize the wheat yield by 24.26%. Generally, the limiting factor for wheat production of the study area was the acidity of the soil. The combined application of lime and compost raised the pH and improved the suitability of the soil for wheat production. However, the status of Av. P was low after the amendment, and it is advisable to integrate phosphorus containing fertilizer in addition to lime and compost for optimum and sustainable production of wheat in the study area. Since the incubation and greenhouse experiment were conducted in a controlled environment, there is a need for field verification. It is also advisable to assess the economic feasibility of the different rates of lime and compost for an appropriate soil management decision.

The intrinsic methane mitigation potential and associated microbes add product value to compost

Conventional agricultural activity reduces the uptake of the potent greenhouse gas methane by agricultural soils. However, the recently observed improved methane uptake capacity of agricultural soils after compost application is promising but needs mechanistic understanding. In this study, the methane uptake potential and microbiomes involved in methane cycling were assessed in green compost and household-compost with and without pre-digestion. In bottle incubations of different composts with both high and near-atmospheric methane concentrations (∼10.000 & ∼10 ppmv, respectively), green compost showed the highest potential methane uptake rates (up to 305.19 ± 94.43 nmol h−1 g dw compost−1 and 25.19 ± 6.75 pmol h−1 g dw compost−1, respectively). 16S, pmoA and mcrA amplicon sequencing revealed that its methanotrophic and methanogenic communities were dominated by type Ib methanotrophs, and more specifically by Methylocaldum szegediense and other Methylocaldum species, and Methanosarcina species, respectively. Ordination analyses showed that the abundance of type Ib methanotrophic bacteria was the main steering factor of the intrinsic methane uptake rates of composts, whilst the ammonium content was the main limiting factor, being most apparent in household composts. These results emphasize the potential of compost to contribute to methane mitigation, providing added value to compost as a product for industrial, commercial, governmental and public interests relevant to waste management. Compost could serve as a vector for the introduction of active methanotrophic bacteria in agricultural soils, potentially improving the methane uptake potential of agricultural soils and contributing to global methane mitigation, which should be the focus of future research.

Different sources of nitrogen fertilizer in rainfed maize grown in a semiarid environment

Although nitrogen is the nutrient most required by maize, doses of N lower than those recommended are applied to maize grown in semiarid environments, which limits the achievement of profitable yields. The objective of this study was to evaluate changes in soil fertility, nutritional status and dry matter production of maize plants fertilized with organic and mineral fertilizers in a semiarid region. A factorial experiment was carried out in Sobral, Ceará state, Brazil, in a randomized block design. The factors were two N sources (organic compost and urea), and four N rates: 27.5, 55, 110 and 165 kg ha−1, with three replications. We assessed variables associated with soil fertility, plant nutritional status, chlorophyll content, grain yield and total dry matter production. The highest rates of organic compost resulted in the highest levels of P (17.7 mg dm−3) and K (102.2 mg dm−3) in soil when compared to the control (7.7 and 69.0 mg dm−3, respectively). However, organic compost rates below 110 kg ha−1 of N-equivalent fertilizer were not enough to supply the plants’ demand for P and K. Low N rates promoted a decrease in soil inorganic N in the second year of application. Applying urea to maize plants led to greater dry matter production than organic compost in the second consecutive crop season. The use of organic compost at rates lower than 110 kg ha−1 of N-equivalent fertilizer decreases soil fertility and has no impact on maize dry matter production.

Indicadores técnicos e econômicos do mamoeiro aos fatores de produção água e composto orgânico

ABSTRACT The objective of this study was to analyze technical and economic indicators of responses of papaya (Carica papaya L.) to the production factors water and organic compost, in a rural property with characteristic of family farming in the Semiarid region of Brazil. The study was conducted from August 2019 to July 2020, in the first crop cycle, in the municipality of Pentecoste, Ceara, Brazil. A Formosa papaya crop (cultivar Tainung 1) was established with spacing of 2.5 × 2.5 m, and irrigated by a micro-sprinkler localized system. A randomized block design was used, with a split-plot arrangement and four replications. The primary treatments consisted of four irrigation water depths (60%, 80%, 100%, and 120% of the crop evapotranspiration), and the secondary treatments consisted of four organic compost rates (0%, 50%, 100%, and 150% of the required rate for the crop). The irrigation water productivity of 5.38 R$ (BRL) m-3, related to the requirements of the production factors, on average, is five-fold the reference value for papaya crops under conventional production system. Rural credit allows the farmer to reach a social reproduction level with a papaya crop area that can be, on average, half of that needed under conditions without financing.

In-field assessment of soil pH and mineralization of phosphorus and potassium following the application of composted winery solid waste in sandy loam Ferric Luvisol

Special attention on the plant nutrients mineralization rates is often required when organic fertilizers are used on croplands. This study described the patterns of phosphorus (P) and exchangeable potassium (K) released from winery solid waste (WSW) compost in sandy loam soil. Treatments consisted of equivalent rates of 0, 5, 10, 20 and 40 t ha-1 of compost-soil mixture in Ziplock bags buried on the field at 30 cm soil depth. Destructive sampling of treatments was conducted at 0, 7, 21, 42, 63, 84, 105 and 126 days after incubation (DAI) for laboratory analysis. The 40 t ha-1rate resulted in up to a 9.5% increase in soil pH while the contents of net mineralized P and K measured were significantly affected by compost rate and incubation period interaction. Over the 126 days of the incubation period that runs across summer and winter seasons, mineralized P ranged from -62 to 86 mg kg-1 whereas mineralized K varied between 41 and 2047 mg kg-1. Cumulative mineralized P and K contents ranged from 62 to 207 mg kg-1 and 1272 to 9206 mg kg-1, respectively with the highest amount obtained at the 40 t ha-1 compost rate. The high net P and K mineralized contents suggest that WSW compost may act as a P and K source. However, cautious use of WSW compost as a soil amendment is recommended to mitigate the potential risks of soil pH increases and other unintended consequences such as toxicity, nutrient imbalance, and possible P and K antagonistic effects. Keywords: Compost; Nutrient mineralization; Phyto-toxicity; Soil amendments