Residue Retention Research Articles

Conservation agriculture's impact on total and labile organic carbon pools in calcareous and non-calcareous floodplain soils under a sub-tropical rice-based system.

To evaluate the effects of conservation agriculture (CA) on SOC pools and their lability, field experiments (2015-2020) were conducted on contrasting soils under subtropical climates. The experiment on non-calcareous soils, was comprised of tillage (minimum [MT] vs. conventional [CT]) in main plots, cropping systems (Wheat [Triticum aestivum]-Aus and Aman rice [Oryza sativa L.], WRR; Lentil [Lens culinaris]-Aus and Aman rice, LRR; and Mustard [Brassica nigra]- Boro and Aman rice, MRR) in the sub-plots, and crop residue (with or without 20% residue) in the sub-sub plots. The experiment on calcareous soils, was comprised of tillage (strip-till, ST; no-till, NT; and CT) and crop residue (high residue, HR at 50% by height vs. low residue, LR at 15%). Results showed that the MT had higher SOC contents by 18.8% than the CT in non-calcareous soils. Likewise, SOC was 12.5% and 6.7% higher in the NT and ST, respectively, than in the CT in calcareous soils. Significantly higher particulate organic (POC), permanganate oxidizable (POXC), and microbial biomass carbon (MBC) were observed in the MT, NT, and ST than in the CT at both locations. Reduced tillage with residue retention under LRR had a higher SOC, including labile C pools compared to WRR and MRR systems. Similarly, carbon management index (1.2-1.5 and 1.0-1.2) in both soils had significant positive correlations with SOC lability via POXC, POC, and MBC pools, indicating a SOC sequestration potential. In conclusion, our results showed positive effects of CA on SOC and its lability across soils.

Effect of residue and weed management practices on weed flora, yield, energetics, carbon footprint, economics and soil quality of zero tillage wheat

A two-year field study was conducted during Rabi 2018–2019 and 2019–20 to find out the influence of different residue and weed management practices on weed dynamics, growth, yield, energetics, carbon footprint, economics and soil properties in zero-tilled sown wheat at Research Farm, AICRP-Weed management, SKUAST-Jammu. The experiment with four rice residue management practices and four weed management practices was conducted in a Strip-Plot Design and replicated thrice. The results showed that residue retention treatments recorded lower weed density, biomass and higher wheat growth, yield attributes and yields of wheat as compared to no residue treatment. The magnitude of increase in wheat grain yield was 17.55, 16.98 and 7.41% when treated with 125% recommended dose of nitrogen + residue + waste decomposer (RDN + R + WD), 125% RDN + R, and 100% RDN + R, respectively, compared to no residue treatment. Further, all three herbicidal treatments decreased weed density and biomass than weedy treatments. Consequently, a reduction of 29.30, 28.00, and 25.70% in grain yield were observed in control as compared to sulfosulfuron + carfentrazone, clodinafop-propargyl + metasulfuron, and clodinafop-propargyl + metribuzin, respectively. Moreover, 125% RDN + R + WD obtained significantly higher energy output (137860 MJ ha−1) and carbon output (4522 kg CE/ha), but 100% RDN had significantly higher net energy (101802 MJ ha−1), energy use efficiency (7.66), energy productivity (0.23 kg MJ−1), energy profitability (6.66 kg MJ−1), carbon efficiency (7.66), and less carbon footprint (7.66) as compared to other treatments. Despite this, treatments with 125% RDN + R + WD and 125% RDN + R provided 17.58 and 16.96% higher gross returns, and 24.45% and 23.17% net outcomes, respectively, than that of control. However, compared to the control, sulfosulfuron + carfentrazone showed considerably higher energy output (140492 MJ ha−1), net energy (104778 MJ ha−1), energy usage efficiency (4.70), energy productivity (0.14 kg MJ−1), energy profitability (3.70 kg MJ−1), carbon output (4624 kg CE ha−1), carbon efficiency (4.71), and lower carbon footprint (0.27). Furthermore, sulfosulfuron + carfentrazone, clodinafop-propargyl + metasulfuron, and clodinafop-propargyl + metribuzin recorded 29.29% and 38.42%, 27.99%, and 36.91%, 25.69% and 34.32% higher gross returns and net returns over control treatment, respectively. All three herbicides showed higher gross returns, net returns, and benefit cost ratio over control. The soil nutrient status was not significantly affected either by residue or weed management practices. Therefore, based on present study it can be concluded that rice residue retention with 25% additional nitrogen and weed management by clodinafop-propargyl + metasulfuron herbicide found suitable for zero tillage wheat.

Tillage and Crop Residue Management on Weed Dynamics and Productivity of Direct Seeded Rice

A field experiment was conducted during 2019 and 2020 to evaluate the effect of tillage and residue management on weed dynamics and productivity of direct seeded rice with four tillage systems; Conventional tillage in rice and wheat, Zero tillage in rice and wheat and two rotational tillage sequences that alternated between Conventional tillage and Zero tillage whereas four residue management practices; residue applied in both season, residue applied in kharif season only, residue applied in rabi season only and without residue in both season. The experiment was carried out at research farm of Birsa Agricultural University, Ranchi, Jharkhand. Results revealed that in direct seeded rice having highest grain yield (10%), straw yield (8%) and yield attributes (10-15%) as well as lesser weed density and weed dry matter found under Conventional tillage during both the seasons of experiment but performance of zero tillage was slightly better (3-4%) in second year as compared to all treatments. Whereas surface retention of residue @5 tonne/ha was significantly more effective in controlling different category of weeds, it decreased up to 60-75% weed population, resulting increment in grain yield up to 19% and 23% during first and second year, respectively, as compared to plot receiving no residue.

Simulating synergistic effects of climate change and conservation practices on greenhouse gas emissions and crop growth in long-term maize cropping systems

Understanding the impacts of future climate change and long-term agronomic practices on environmental quality and agricultural productivity is critical to the development of sustainable agronomic management approaches. Given these requirements, the present study’s objective was to evaluate the potential impacts of climate change and long-term conservation practices on greenhouse gas (GHG) emissions and crop growth. To project potential future (2065–2084) climatic conditions for a field under a long-term maize cropping system situated in Nebraska (USA), 12 different combinations of regional climate models × global climate models (RCMs-GCMs) were generated under representative concentration pathway 8.5 (RCP8.5) and a heightened atmospheric carbon dioxide concentration ([CO2]atm = 714.1 ppm). Then, employing a well-calibrated instance of the Root Zone Water Quality Model (RZWQM2), the effects of four long-term conservation practices were simulated under the 12 RCMs-GCMs. Compared to other climatic factors (e.g., shortwave radiation, wind run, and relative humidity), temperature, precipitation, and [CO2]atm played more important roles for future carbon dioxide (CO2) and nitrous oxide (N2O) emissions, global warming potential (GWP), soil organic carbon (SOC), crop yield, and total crop biomass. The sum of their relative contributions to GHG emissions and crop growth exceeded 83.9 % across all treatments. Under future climatic conditions, CO2 and N2O emissions increased significantly — 19.4 % ± 5.8 % and 26.6 % ± 8.9 %, respectively — compared to those under historical baseline conditions. Likewise, the GWP increased by 19.8 ± 5.8 %. Although rising [CO2]atm afforded limited benefits in terms of crop photosynthesis rates, rising future temperatures shortened crop growth cycles, resulting in a net decrease of 9.1 % ± 1.9 % in maize yield and 4.2 % ± 1.6 % in total biomass. SOC saw a net increase of 4.8 % ± 0.4 % under the future (vs. baseline) climate. Compared to residue removal with no-till treatment, annual CO2 and N2O emissions in the long-term maize cropping system were predicted to increase by 26.8 % and 27.9 % between 2065 and 2084 under residue retention with tillage treatment, respectively. Whereas crop yield and biomass were not significantly affected by residue or tillage management practices. The simulation method provided valuable evidence for management decisions to assess the synergistic effects of climate change and long-term agronomic practices on the environment and agricultural productivity. Further investigation is needed on the effects of other climate RCPs and agronomic management for sustainable agricultural production.

Long-term residue retention affects seedcotton yield by regulating distribution of photosynthetic carbon, boll capacity of the root system and soil quality

Long-term residue retention affects seedcotton yield by regulating distribution of photosynthetic carbon, boll capacity of the root system and soil quality

Influence of crop residue and nitrogen management on nutrient uptake, yield, and economics of rice-wheat cropping system

The present investigation was conducted to find out optimize Nitrogen (N) dose and its scheduling to achieve nutrient uptake and higher productivity of ZT wheat with residue retention at the research farm of CCSHAU, Regional Research Station (RRS), Karnal during rabi seasons of 2019–2020 and 2020–2021. The field experiment comprised four main plot treatments viz., Zero tillage wheat-Happy seeder (ZTW-HS) with full residue (chopped), ZTW-HS with full residue (unchopped), ZTW-HS with partial residues (anchored stubbles), and conventional tillage wheat- drill sown (CTW-DS) with full residue (chopped); and six sub-plots having two N levels viz., 150 and 180 kg/ha applied into 2 and 3 splits, i.e. at sowing, before 1st irrigation, after 1st irrigation, and after 2nd irrigation. ZTW-HS with full residue (unchopped) in wheat increased the grain yield of wheat by 9.18% more than CTW-DS with full residue (chopped). Three N-splits, i.e. at sowing, before 1st irrigation and after 1st irrigation in wheat increased grain yield of wheat by 8.08% more than 2 splits, i.e. at sowing and after 1st irrigation. ZTW-HS with full residue (unchopped) with N@150 kg/ha with 3 splits, i.e. at sowing, before 1st irrigation and after 1st irrigation provides the best combination effect and improved the nutrient uptake in grain and straw, N, Phosphorus (P), Potassium (K), and yield of wheat and provide high economic returns.

Crop–weed dynamics, nutrient uptake, and soil microclimate in elephant foot yam under conservation agriculture

Conservation agriculture (CA) is a sustainable option to adapt to climate change. Weed management is one of the most important challenges faced by CA. Information on CA in cropping systems involving elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson), an important tuber crop, is lacking. Hence, this study aimed to determine the effect of CA in elephant foot yam on crop–weed dynamics, nutrient uptake, and soil microclimate. Field experiments were conducted in randomized block design over two seasons at ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala, India, in elephant foot yam (var. Gajendra) intercropped with banana (var. Robusta) with five treatments viz., conservation organic, conservation chemical, conventional chemical, existing conventional [package of practices (POP) as control], and existing organic package. The weed flora was dominated by broad-leaved weeds. By the fourth month, conservation chemical practice reduced the weed density by 58.8% and weed biomass by 55% over existing POP. The total biomass production and its partitioning to corms, uptake of nitrogen (N), phosphorus (P), and potassium (K), crop growth rate, corm bulking rate, and harvest index of elephant foot yam did not differ significantly under conservation or conventional practices but were higher in conservation chemical practice. The N, P, and K physiological efficiencies were higher in conventional chemical treatment. The soil microclimate was improved, with higher soil CO2 flux and soil moisture in conservation organic or organic plots. The study proved that conservation practices involving reduced tillage, residue retention, and use of herbicides was a viable alternative in banana + elephant foot yam system.

Boosting wheat yield, profitability and NUE with prilled and nano urea in conservation tillage

Rice–wheat production in the Indo-gangetic plains (IGPs) of India faces major concerns such as depleting resources, rice residue burning, excessive fertilizer use, and decreasing nitrogen use efficiency. These issues threaten sustainable crop production in the future. Therefore, a field study was conducted during the winter seasons of 2020–21 and 2021–22 to evaluate the effect of combined conventional and nano fertilizers on nitrogen application just before or after irrigation to improve wheat productivity, profitability and NUE under conservation tillage. The study evaluated eight treatment combinations of nitrogen application through conventionally applied urea (46% N) and foliar applied nano urea (4% N) under zero tillage with rice residue retention. Results revealed that growth, physiological indices, yield, and quality parameters were enhanced with the application of 150 kg N/ha in three equal splits as basal and just before 1st and 2nd irrigation alone (T2) or along with a spray of nano urea (T5) compared to other treatments. T5 recorded 7.2%, 8.5%, and 7.8% more plant dry matter, number of tillers, and grain yield, respectively, over the conventional practice of applying 150 kg N/ha in three equal splits as basal and 7–10 days after 1st and 2nd irrigation (T3, farmers practice). Although, T2 showed similar results to T5, T5 recorded significantly higher gross ($2542/ha) and net returns ($1279/ha) than the other treatments. However, the benefit–cost ratio of T2 and T5 was same (2.01). A significant and positive correlation coefficient between grain yield and physiological parameters such as CCI and NDVI confirmed that increasing the nitrogen dose enhanced the chlorophyll content, greenness, and plant vigor. Based on the results, it can be concluded that applying 150 kg N/ha in three equal splits as basal and just before 1st and 2nd irrigation under conservation agriculture, along with a single spray of nano urea (4% N) at 60–65 days after sowing, can improve growth, yield attributes, wheat yield, and NUE compared to farmers practice (T3) in India.

Effect of Different Tillage and Residue Management Options on Soil Water Transmission and Mechanical Behavior

Understanding the variability in the mechanical and hydrological soil characteristics resulting from diverse tillage and residue management practices is essential for evaluating the adoption of conservation strategies to preserve soil’s physical well-being. Zero-tillage techniques combined with residue retention or incorporation have gained widespread recognition for their capacity to conserve soil and water resources, reduce energy consumption, and enhance soil quality and environmental sustainability. Nevertheless, the choice of tillage and residue management options may vary depending on the geographical locations and specific soil conditions. To assess the impacts of four distinct tillage and residue management approaches, a two-year experiment (2020–2021 and 2021–2022) was conducted: T1: conventional tillage followed by wheat sowing after the removal of rice straw (CT-RS); T2: zero tillage with wheat sowing using a Happy Seeder while retaining rice straw (ZT+RS); T3: conventional tillage followed by wheat sowing after rice straw incorporation using a reversible mouldboard plough (CT+RS); T4: minimum tillage with wheat sowing using a Super Seeder with rice straw incorporation (MT+RS); the effects were recorded on the physical soil properties. Our findings indicate that zero tillage combined with residue retention (T2) had a positive influence on various physical soil attributes. Notably, significant differences were observed among the tillage and residue management options, particularly in terms of the bulk density with T1 exhibiting the highest values and the lowest being in T2, whereas the soil penetration resistance was lowest in T3 compared to T1. In the case of T3, sandy loam and clay loam soils had the highest measured saturated hydraulic conductivity values, measuring 5.08 and 4.57 cm h−1 and 4.07 and 3.73 cm h−1, respectively. Furthermore, T2 (zero tillage with residue retention) demonstrated the highest mean weight diameter (MWD) and maximum water stable aggregate. These results collectively underscore the positive effects of adopting zero tillage and retaining residue (T2) on soil structure and quality, particularly concerning the mechanical and hydrological soil properties.

Deciphering the role of phosphorus management under conservation agriculture based wheat production system

Phosphorus (P) is a vital element required by all living organism (plants, animals and microbes etc.). Its application in agriculture, whether in conventional or conservation agriculture, requires careful attention due to its low use efficiency, which typically does not exceed 20%. With the increasing acceptance of conservation agriculture (CA), it is crucial to develop protocols for P management to ensure sustainable wheat production. Therefore, a field trial was conducted from 2016–2017 to 2017–2018 in the India's semiarid eco-region to study the role of P on wheat productivity, quality, and resource use efficiency under CA-based production system. We assessed the impact of tillage operations and P management practices on wheat productivity, quality, and resource use efficiency. Three tillage and residue management options such as CT-R (conventional tillage without residue); NT-R (no tillage without maize residue) and NT + R (no tillage with maize residue @ 2.5 Mg ha−1) were laid-out in main plot and five P management options subplots viz. P1 (nitrogen and potash according to recommended but not P); P2 (17.2 kg P ha−1); P3 (17.2 kg of P ha−1 + microbial fertilizer); P4 (17.2 kg P ha−1 + compost inoculant culture) and P5 (34.4 kg P ha−1) in split plot design with three replicates. The results indicates that the combination of no-tillage with residue retention (maize residue @ 2.5 Mg ha−1) (NT + R) and the application of 34.4 kg P ha−1 (P5) significantly improved grain yield by ~43.2% compared to the control treatment (conventional tillage with no residue, CT – R, and no phosphorus application). NT + R also resulted in significantly better amino acid (~22.7%) and net protein yield (~21.2%) compared to CT – R. Regarding the P management strategy, the highest amino acid (49.1%) and protein yield (12.5%) were observed under the P5 treatment compared to the no-phosphorus treatment. Conjoint use of NT – R, along with the application of 17.2 kg P ha−1 and PSB (Phosphorus Solubilizing Bacteria), resulted in a significant increase in energy use efficiency of ~58% over other treatments combination. Furthermore, the NT + R plot that received 17.2 kg P ha−1 + PSB demonstrated higher P agronomic efficiency (~43%) and recovery efficiency (~53%) over control. The study's findings underscore the significance of adopting efficient P management strategies in CA to ensure the sustainable production of wheat.

Usage of Agroecological Climate-Smart Agriculture Practices among Sorghum and Maize Smallholder Farmers in Semi-Arid Areas in Tanzania

Climate change variability and its impact on agricultural production in sub-Saharan Africa pose a significant challenge to food security. In Tanzania's semi-arid regions, there is growing concern regarding the use of agroecological Climate-Smart Agriculture (CSA) practices by smallholder farmers that adhere to agroecological principles. This study aimed to investigate the use of agroecological CSA practices among smallholder farmers in Tanzania's semi-arid regions, specifically in Dodoma and Tabora regions. In addition, this study sought to identify the key factors influencing the use of these practices to enhance food security, income, and climate resilience. Data were collected from 299 households in Dodoma and Tabora using various methods including questionnaire surveys, focus group discussions, and key informant interviews. Binary logistic regression was used to analyse factors influencing the usage of agroecological climate-smart agriculture practices. The findings revealed that most households in the study area use agroecological CSA practices. These practices include cereal-legume intercropping, mixed cropping, crop residue retention, crop rotation, and improved seed variety. Water harvesting, terraces, and cover crops were not used by many households. Several factors positively influenced the use of agroecological CSA. They include assistance from non-governmental organizations (NGOs), training in CSA practices, drought perception, access to credit, distance to market, membership in an organisation, education level of the household head, and total household income. To promote the use of agroecological CSA practices, both governments and NGOs should prioritise training programs. Moreover, providing frequent extension services and facilitating easier access to credit for farmers can further support the widespread use of these practices. In doing so, local communities can adapt better to the challenges of climate change, ensuring improved food security and climate resilience in the region

Organic soil fertility management practices for the management of fall armyworm, Spodoptera frugiperda (J.E. Smith), in maize.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a polyphagous pest native to the Americas. It attacks several crops but in particular causes significant damage to maize, which is a staple crop in Africa. Organic soil amendments have an impact on the physical, chemical, and biological properties of soil, which enhance plant resistance to or tolerance of insect pests and also promote a diverse population of natural enemies of the pest. However, the practices followed for the management of crop residue and animal manure affect their use as organic soil amendments. A field experiment was conducted to evaluate the effect of maize residue and cattle manure incorporation into soil on FAW in the Mana and Omo Nada districts of the Jimma zone, southwest Ethiopia, during the 2018/19 cropping season. Treatment involved three factors: five different levels of maize residue retention (0%, 25%, 50%, 75%, and 100%), different cattle manure storage systems (control, open, steel roof, and grass roof), and two different districts (Mana and Omo Nada). These variables were organized in a randomized complete block design and replicated three times. The infestation and damage ratings were collected from 30 days after planting at 20-day intervals. The results indicated that maize plots with retained crop residue had a significant reduction in FAW infestation compared with plots without maize residue (control) in both study districts. Furthermore, manure-fertilized plants had a lower percentage of FAW infestation when compared with maize plots without cattle manure in both study districts. The lowest severity of FAW infestation was recorded in a plot with 100% of residue incorporated and treated with cattle manure stored under a grass roof in the Mana district. Therefore, conventional tillage with 100% maize residue incorporation and the application of cattle manure stored under a grass roof showed the best result for reducing FAW infestation in maize. However, further studies are important to determine the effect of treatments over seasons and locations on FAW infestation and maize yields.

Crop residue retention increases greenhouse gas emissions but reduces chemical fertilizer requirement in a vegetable-rice rotation

Retaining crop residues on site after harvesting can maintain soil fertility, reduce fertilizer requirements and restore soil organic carbon on intensively cultivated land. However, how crop residue retention and reduced chemical fertilizer application affect greenhouse gas emissions and crop yield in vegetable-rice rotations is poorly understood. We studied the effect of chemical fertilizer application alone (control, without straw retention), straw retention with 100 % nitrogen fertilizer application (STF) or with three levels of reduced chemical fertilizer application (SFR1, SFR2 and SFR3) in a vegetable-rice rotation in a mesocosm system. In the vegetable season, crop yield was maintained but the agronomic efficiency (AE) was higher in SFR1, SFR2 and SFR3 as compared to STF and the control. In the rice season under flooded condition, the methanogens were higher in SFR1, SFR2 and SFR3 compared to the control, but not different between STF and SFR1. The STF showed higher methane and nitrous oxide emissions, but carbon dioxide emissions and AE remained unaffected compared to the control in the vegetable-rice rotation. The SFR2 and SFR3 treatments maintained crop yields, increased AE, and decreased N2O emissions as compared with STF, but the CH4 emissions were 29.8 % lower in SFR2 than SFR3 in the vegetable-rice rotation. We concluded that straw retention with reduced chemical fertilizer application can maintain crop yield in a vegetable-rice rotation but has the potential to increase CH4 emissions in the rice cultivation season.

Long-term adoption of bed planted conservation agriculture based maize/cotton-wheat system enhances soil organic carbon stabilization within aggregates in the indo-gangetic plains

Sustainability of contemporary crop establishment and management practices is questioned due to soil degradation, higher carbon emission and declining soil productivity. Hence, this study was conducted to address the impacts of conservation agriculture (CA) practices like permanent broad beds (PBB), permanent narrow beds (PNB) and zero tilled flat beds (ZT) with residue retention on soil organic carbon (SOC) protection within aggregates in the Indo-Gangetic Plains (IGP). Compared to conventionally tilled (CT) plots, the total SOC content was ∼27%–33% higher in the CA plots on equivalent mass basis. The soil physical properties, such as soil aggregation and mean weight diameter were considerably improved under the CA practices. The macroaggregates were ∼41, 37% and 27% higher in the PBB with residue (PBB + R), PNB with residue (PNB + R) and ZT with residue (ZT + R) plots (CA plots), respectively, than the CT plots in the surface soil (0–15 cm). The plots under PBB + R had ∼31% higher microaggregates within macroaggregates than the CT plots (24.4 g 100 g−1) soil. An increase in SOC content by ∼72, 55% and 69% was observed in the PBB + R, PNB + R and ZT + R plots over the CT plots in microaggregates within macroaggregates (3.02 Mg ha−1). However, plots under PBB + R, PNB + R and ZT + R had only ∼11, 3% and 23% more SOC within silt + clay fraction, respectively, than CT plots (5.85 Mg ha−1). Thus, SOC stabilization within microaggregates inside macroaggregates was the major mechanism, and not the chemical stabilization within silt + clay, of C sequestration under CA. As aggregate-associated carbon is an ecosystem property that strongly affects organic carbon stabilization, water holding capacity and resistance to erosion, growing maize/cotton–wheat system under PBB + R practice is a viable option for carbon sequestration in the IGP and similar agro-ecologies.

Crop Residues Management: A Viable Tool for Sustainable Agriculture

The crop residue, traditionally considered as agricultural waste, is increasingly being viewed as a valuable resource. If the current trend continues, crop residue will be a “co-product” of grain production where both the grain and the residue have significant value. Potentially gross quantities of over 500 Mt crop residues are available in India on an annual basis and generated by various crops. Due to the scarcity of alternative organic amendments, the retention of crop residue in fields can be considered key in promoting physical, chemical, and biological attributes of soil in the agricultural systems of developing countries. The stems, leaves, chaffs, husks, etc., that remain in the fields after crops are harvested, play a critical role in soil quality and environmental issues since they are primary inputs of elemental carbon (C) into the soil system. About 25% N, 25% P, 75% K and 50% S uptake by cereal crops are retained in residues, making them valuable sources of nutrients.

Influence of Different Residue Retention and Nutrient Levels on Crop Productivity of Soybean (Glycine max L.) under Conservation Agriculture

During the kharif season of 2020-22, a field experiment with soybean in a soybean-wheat cropping system was conducted at the ICAR-Indian Institute of Soil Science, Bhopal, (M.P.) to assess the effect of different levels of crop residue retention treatments and nutrient doses on growth parameters, physiological indices, yield attributes, yield and profitability of soybean. The experiment was laid out with Factorial Randomized Block Design (FRBD) comprised of 16 combinations of 4 residue level (0%, 30%, 60% and 90%) and 4 nutrient doses (N1-RDF (120:60:40 kg N, P2O5 and K2O ha-1), N2-75% N+100% P2O5 and K2O ha-1, N3-75% P2O5+100% N and K2O ha-1, N4-75% K2O+100% N and P2O5 ha-1) with 3 replication under ongoing CRP-CA (Consortium Research Platform on Conservation Agriculture). The result showed that growth parameters, physiological indices as well as yield, yield attributes and profitability were significantly higher in 90% than other crop reside retention treatment. The higher (90%) crop residue retention resulted in 16% higher grain yield, 16.88% stover yield and 17.55% higher profitability then without residue treatment. Among different nutrient doses 100% RDF showed significantly higher growth and better physiological indices at all the growth stages. Significantly higher seed (1226 kg ha-1) and stover (2274 kg ha-1) yields were recorded with 100% RDF with any other management practices.

Applying circular economy principles to intensification of livestock production in Sub-Saharan Africa

In the context of sustainable agricultural development, much has been made of the need to apply agroecology or regenerative principles to improve rural livelihoods and to align the sector with critical planetary health boundaries. This movement is a reaction to the perceived private and social costs arising from both production and consumption associated with industrialised agriculture, mostly in upper-income countries, with several default assumptions being apparent about applicability elsewhere. The notion of circularity, or the circular economy, is frequently conflated with agro ecological rhetoric, often overlooking a longer tradition of circular resource use efficiency in traditional mixed crop–livestock farming in low-income settings. This paper examines the concept and origins of circularity and reviews some examples of historic circular economy research within the international agricultural research system as applied to smallholder agriculture. These include (i) studies focusing on the impact of crop residue retention, (ii) work on residue incorporation and/or mulching and their effects on crop yields and soil fertility, (iii) research on the effects of manure use on crop yields and soil fertility and (iv) work on the feeding of crop residues to livestock. We consider some promising innovations or practices adhering to circular economy principles. Candidate innovations focus on the improvement of livestock feeding practices including the breeding of dual-purpose crops to enhance livestock nutrition, conversion of cereal straw residues to high-quality feed, use of cassava waste as livestock feed and use of insects as livestock feed. We conclude by considering how circular bio-economy principles might be maintained in the future evolution of food systems in Sub-Saharan Africa.

Effects of Different Tillage and Residue Retention Measures on Silage Maize Yield and Quality and Soil Phosphorus in Karst Areas

Soil phosphorus (P) limitation in karst areas has severely constrained soil quality and land productivity. To enhance silage maize yield and quality and alleviate and/or balance the low phosphorus availability in the karst areas of China, the experiment investigated the effects of different tillage and residue retention practices on silage maize yield and quality and soil phosphorus in this region. The treatment set included: conventional tillage (CT), conventional tillage and root stubble retention (CTH), conventional tillage and mulch (CTM), conventional tillage and crushing and incorporation of hairy vetch by tillage (CTR), no tillage (NT), no tillage and root stubble retention (NTH), no tillage and mulch (NTM), and no tillage and living mulch (NTLM). The results showed that CTM, NTM, CTR, and NTLM significantly increased the height and LAI of silage maize compared with the CT, NT, and NTH treatments. CTM, CTR, and NTM significantly enhanced maize yield. Compared with conventional tillage, not tilling had a more pronounced improvement in silage quality, whereas residue retention hardly affected corn quality. In addition, although not tilling does not significantly increase acid phosphatase activity, it appeared to be advantageous in increasing soil microbial phosphorus and available phosphorus content when combined with cover crop measures. Ultimately, we concluded that NTM and NTLM are beneficial for silage maize yield and quality and soil phosphorus content in karst areas and verified the advantages of combining no tillage and residue retention practices for silage maize production and soil phosphorus improvement in the karst areas of China.

Conservation agriculture impacts on soil carbon sequestration under a cotton (Gossypium hirsutum)-wheat (Triticum aestivum) system in the Indo-Gangetic plains

Despite many studies reporting conservation agriculture (CA) impacts on soil organic carbon (SOC) sequestration, the impacts of long-term permanent bed planting under CA on SOC sequestration are rarely reported. Hence, this study assessed the permanent bed planted CA impacts on SOC sequestration rates in 0–30 and 30–60 cm soil depths under a cotton (Gossypium hirsutum L.)-wheat (Triticum aestivum L.) system in the Indo-Gangetic Plains (IGP). The treatments comprised diverse combinations of tillage and residue retention (R), viz. conventional tillage (CT), narrow bed, narrow bed + R, broad bed, broad bed + R, flat bed + R and flat bed. Results indicated that the total SOC stock was ~32, 31 and 29% higher in CA plots than in CT plots (farmers' practice), in 0–30 cm soil depth. The SOC sequestration rate (over CT plots) in the CA plots was ~0.76 Mg C/ha/yr. The broad bed + R, narrow bed + R and flat bed + R plots had appreciably high total SOC sequestration (~0.24 Mg C/ha/yr) compared to CT plots in deep soil layer (30–60 cm). The yield data (2-year mean basis) was recorded highest in the broad bed + R (3.48 tonnes/ha and 8.11 tonnes/ha for cotton and wheat, respectively) and flat bed + R (3.38 tonnes/ha and 8.46 tonnes/ha for cotton and wheat, respectively) treatments showing a positive impact of the adoption of long-term CA in the IGP. Thus, adopting raised beds with residue retention has great potential for higher carbon sequestration and improving yields and can be recommended for sustainable intensification of arable lands in the region.

Influence of tree residue retention in Mediterranean forest on soil microbial communities responses to frequent warming and drying events

In the coming decades, Mediterranean forests are likely to experience higher heat-wave frequency that may severely affect soil microbial functioning. Here, we studied the effects of warming intensification on soil microbial communities and tested whether certain types of Mediterranean plant residues favor soil biological resistance to frequent drying and warming events (FDW). To this aim, we set-up mesocosms in which soils originating from six Mediterranean forest stands (i.e, Quercus ilex and Q. pubescens and Pinus halepensis and P. sylvestris monospecific and mixed stands) were amended with corresponding coarse (crushed branches) and fine (crushed twigs with leaves/needles) woody debris. A quantity of residues corresponding to five-fold the equivalent of the quantity left on the floor after tree harvesting/logging (equivalent to 35 gC.kg−1 soil DW) was added to each pot, and mesocosms were laid out into a split-plot design and subjected to FDW. After nineteen months, soil physico-chemical properties and changes in microbial communities' diversity and structure, biomass and extracellular enzymatic activities were measured. We showed that FDW reduced the richness of the soil fungal community by ca. 11% and functional diversity by ca. 4% and increased bacterial richness by ca. 40%. We observed a drastic down-regulation of extracellular enzyme activities related with N and C cycles (respectively -44% for protease, -54% for cellulase and -31% for tyrosinase activities). We also found that residues inputs types (fine vs. coarse) only slightly mitigate those effects, while species origin did. Our study showed that residues retention could alleviate the consequences of hydric and thermic stresses on microbial communities by modulating communities’ resistance in specific stands. These results suggest that tree residues retention, in specific stands, could contribute to sustain soil biological properties in the context of Mediterranean climate intensification.