Stubble Management Research Articles

Stubble burning: Root cause, impacts and its management in Indian scenario

The practice of purposefully setting fire to the residue that remained after harvest of rice and wheat crop is increasing periodically. Stubble burning has become one of the challenging issues in India in recent times. Government has been consistently instructing farmers not to burn the crop residues, instead asking them for in-situ management. Farmers are citing various complications in stubble management which pulling them to setting up fire to the stubble. Rice straw burning generates life threatening greenhouse gases which causes air pollution injury. Particulate matter (PM2.5) levels in the capital state of India (New Delhi) have been exceeded by 14 times than threshold level because of episodic agricultural fires in the neighbouring states namely Punjab, Haryana. A very limited study has been done so far on this complete issue despite of its importance. The present review tried to expose root cause, impacts on ecosystem and management strategies of stubble burning especially in India. There are plethora of possibilities in managing residue in sustainable ways including in-situ residue management, mushroom production, livestock feed, composting, biochar preparation, bio-thermal power plants and paper industries. Mechanical and effective method of in-situ management has been come into existence in the form of happy seeder. Depending on the land holding farmers can follow any of the said methods and manage their residue in sustainable way by overcoming the constraints thereby reducing the impacts on ecosystem.

Effect of Tillage System and Organic Matter Management Interactions on Soil Chemical Properties and Biological Activity in a Spring Wheat Short-Time Cultivation

Properly selected tillage methods and management of the available organic matter resources are considered important measures to enable farming in accordance with the principles of sustainable agriculture. Depending on the depth and intensity of cultivation, tillage practices affect soil chemical composition, structure and biological activity. The three-year experiment was performed on the soil under spring wheat (cv. Tybalt) short-time cultivation. The influence of different tillage systems and stubble management on the soil’s chemical and biological parameters was analyzed. Organic carbon content (OC); content of biologically available phosphorus (Pa), potassium (Ka), and magnesium (Mg); content of total nitrogen (TN), mineral nitrogen forms: N-NO3 and N-NH4 were determined in various soil samples. Moreover, the total number of microorganisms (TNM), bacteria (B), actinobacteria (A), fungi (F); soil respiratory activity (SR); and pH in 1 M KCl (pH) were also investigated. The results show that organic matter amendment is of greater influence on soil characteristics than the tillage system applied. Manure application, as well as leaving the straw in the field, resulted in higher amounts of organic carbon and biologically available potassium. A significant increase in the number of soil microorganisms was also observed in soil samples from the experimental plots including this procedure.

An Overview of Crop and Crop Residue Management Impacts on Crop Water Use and Runoff in the Canadian Prairies

Although crop and crop residue management practices are mainly used for increasing crop yield, they and the resulting changes in crop growth affect one or more hydrological components, including runoff. Based on published research in the Canadian Prairies, this paper reviews the effects of crop type, quantity of crops and crop residues, crop variability within landscapes, tillage, and stubble management practices on crop water use (termed including evaporation, transpiration and interception), snow trapping, and water infiltration, with the aim to discuss major impacts of crop and residue management on runoff. Rainfall runoff is influenced by rain interception and crop water use, and it can be reduced by choosing appropriate crop types, increasing above-ground biomass, or increasing coverage on the soil surface, activities which coincide with the farmer’s efforts of increasing crop productivity. However, although high stubble and reduced tillage for maintaining good residue cover help conserve soil moisture and improve soil health, they increase snowmelt runoff potential. The review emphasizes the need of future research to assess the agronomic and environmental trade-offs of crop residue management, the linkage between crop water use and runoff, and the impacts of crop and residue management on runoff across various temporal and spatial scales.

Biological activity of chitosan inducing resistance efficiency of rice (Oryza sativa L.) after treatment with fungal based chitosan

Reduced pathogen resistance and management of the left-over rice stubble are among the most important challenges faced in rice cultivation. A novel and eco-friendly strategy to synthesise ‘Fungal Chitosan’ (FC) from Aspergillus niger using rice straw could serve as a sustainable treatment approach to improve both disease resistance and yields, while also effectively managing the rice stubble waste. The FC treatment promoted germination as well as growth parameters in rice varieties, TN1 (high yielding-susceptible) and PTB33 (low yielding-resistant) better than a commercial chitosan (PC). Treatments of exogenously applied FC to plants produced direct toxicity to Xoo, and reduced the BLB disease index by 39.9% in TN1. The capability of FC to trigger a cascade of defense pathways was evident from the measurable changes in the kinetics of defense enzymes, peroxidase (POD) and polyphenol oxidase (PPO). FC treatment increased levels of POD in TN1 by 59.4%, which was 35.3% greater than that of untreated PTB33. Therefore, the study demonstrated the effectiveness of FC treatments for use in agriculture as a potential biostimulant as well as protective agent against bacterial leaf blight, BLB, of rice (Oryza sativa) that could be produced from stubble waste and improve rice stubble management strategies.

Unraveling microbiomes and functions associated with strategic tillage, stubble, and fertilizer management

Occasional one-time tillage (strategic tillage, ST) is an effective tool for managing weeds and crop diseases in no-till and conversative farming systems. However, there is limited understanding of the impacts of ST on soil microbiome and their associated soil processes, particularly in dryland agriculture. This study aims to quantify the effect of one-off ST - after three years - on soil microbiomes and functions in a long-term no-till farming system under crop stubble and fertilizer management practices. The results showed that ST had marginal effects on microbial richness and diversity, enzyme activities, and catabolic function, but significantly affected the abundance of some microbial taxa (Actinobacteria, Firmicutes, Verrucomicrobia, Basidiomycota and Ascomycota) that are relevant to carbon (C) degradation. Stubble retention, regardless of tillage and fertilizer management, mainly increased the abundance of copiotrophs such as Proteobacteria (e.g., Rhizobiales) and Actinobacteria (e.g., Streptomyces and Micromonosporaceae), and affected Ascomycota and Basidiomycota. Among the management practices, stubble retention was the main factor that contributed to increased richness and diversity of the soil bacterial and fungal community. Supplementary fertilizer application, regardless of tillage and stubble management had minimal impact on bacterial and fungal richness and diversity, enzyme activity and catabolic function. The variation in bacterial community structure was influenced mainly by soil pH (c.a. 10%), while only a small but significant effect (< 7%; P = 0.001) was attributed to tillage and stubble management. Wheat grain yields ranged between 5 and 5.3 t ha-1 and were not affected by tillage, stubble, nor fertilizer management practices. Similarly, these management practices did not influence total soil C or nitrogen concentrations. Our findings show that strategic tillage, when used to address specific constraints in no-till systems in dryland agriculture, does not have a significant effect on total soil C, microbial ecology nor catabolic function.

The Cumulative Effect of Various Tillage Systems and Stubble Management on the Biological and Chemical Properties of Soil in Winter Wheat Monoculture

Agricultural practices, including tillage systems and postharvest residue management, strongly affect a wide range of soil properties. Depending on the degree of soil inversion, both negative and beneficial changes of its structure, chemical composition, and biological activity may occur as a result of these treatments. The three-year experiment was carried out on the soil under winter wheat (cv. Arktis) monoculture. The effect of various tillage systems and stubble management on the soil environment’s biological and chemical features was investigated. The total number of microorganisms (TNM); bacteria (B); actinobacteria(A); fungi (F); soil respiratory activity (SR); pH in 1 M KCl (pH); organic carbon content (OC); content of available phosphorus (Pa); potassium (Ka); magnesium (Mg); and content of total nitrogen (TN) and mineral nitrogen forms were determined in soil samples. It was shown that manure application was the factor with the greatest influence on soil properties. The manure fertilization resulted in a higher number of microorganisms in arable soil. Conventional tillage procedures combined with manure application increased the amounts of available forms of phosphorus, potassium, magnesium, and mineral nitrogen. Introduction of the chopped straw in the field enhanced the beneficial effect of manure on soil properties.

50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a Vertisol

Farm management practices such as no-tillage, stubble retention, and nitrogen (N) application have a substantial potential to enhance soil aggregation in agricultural soils. This is especially important for Vertisols, which may experience extended waterlogging due to low infiltration rates and low hydraulic conductivity. We evaluated the long-term impacts of the tillage method (no tillage, NT, and conventional tillage, CT), stubble management practices (stubble retention, SR, or stubble burning, SB) and N-fertilization on aggregate size distribution, and distribution of total C and N within different aggregate-size fractions in a Vertisol. Soil samples were collected from 0–0.1 m depth at the Hermitage Research Station in Queensland, Australia, after 50 years of management. We found that the soil under NT with SR and 90 kg N fertilizer application (NTSRN90) contained the highest proportion of large macro-aggregates (31.0 %), the greatest mean weight diameter (MWD) (1.79 mm), and the highest percentage of water stable aggregates (WSA, 90.2 %), whilst the lowest values (3.15 %, 0.71 mm and 72.7 %, respectively) were found in the CTSBN0 treatment. Therefore, reducing soil disturbance by primary tillage operations (NT) and the retention of crop residues (SR) and fertilizer application stimulated the formation of soil macro-aggregates from micro-aggregates. Retention of higher amounts of residues to the system in the SR and N fertilized treatments increased the macro-aggregate occluded particulate organic C (POC) and N (PON), which likely provided loci for aggregate formation and binding agents for stabilisation. Larger aggregates stored more organic C and N, and had lower water retention at saturation (−10 kPa), than smaller aggregates or the silt + clay fraction, thus having the potential to reduce the frequency of waterlogging in the soil under NT, SR, and N fertilization. Therefore, long-term practice of no-tillage along with stubble retention and N fertilisation could significantly enhance the macro-aggregation of fine-textured Vertisols, with this then ensuring the sustainability of the agricultural production system by creating favourable water retention and movement, and porosity for better management for crop production.

Changes in soil properties and crop performance on stubble-burned and cultivated water-repellent soils can take many years following reversion to no-till and stubble retention

No-tillage and stubble retention have been widely adopted in south-western Australia to protect agricultural soils from erosion, but potentially exacerbate repellency. In a 10-year (2008–2017) field experiment, 4 combinations of tillage (no-till vs cultivation) and stubble management (retention or burning) were applied annually from 2008 to 2011. In 2012, all plots were returned to no-till and stubble retention to determine the recovery of crop performance and soil properties from stubble burning and/or cultivation, and this recovery phase is reported here. Changes to ground cover, soil water repellency, soil water content, soil carbon and crop performance during a 6-year period (2012–2017) were compared with plots where no-tillage and stubble retention had been practised for several decades. At the conclusion of monitoring in 2017, ground cover (average 55%) and soil carbon (average 1.2%) in the previously burned treatments remained significantly (P < 0.05) less than in treatments where stubble had always been retained (average ground cover 68% and soil carbon 1.7%). Soil water repellency (Molarity of Ethanol Drop (MED)) varied with seasonal conditions but was always highest (P < 0.001) in the treatment which had been continuously no-till, stubble retained (MED 1.7 in 2017) compared with the treatment that was previously burned and cultivated (MED 1.0 in 2017), but this did not influence soil water contents which were generally higher (P < 0.05) in the more repellent soils. The effect of previous tillage treatment on soil water contents resolved quickly after the reversion to no-tillage, likely due to the rapid establishment and preservation of root pathways to aid water infiltration. However, the effect of stubble burning on soil water contents remained significant (P < 0.001) with 2% v/v less water in 2017 in previously burned treatments compared with those where stubble had always been retained. Average grain yields where stubble had always been retained were significantly (P < 0.001) greater by 22–33% than where stubbles had previously been burned in 4 of the 6 seasons. The poor recovery in crop performance in the previously stubble-burned treatments was attributed to the slow build-up of soil carbon to support water- and nutrient-holding capacity, and crop residue ground cover to protect soils from water loss and erosion.

Wheat-Paddy Straw Biochar: An Ecological Solution of Stubble Burning in the Agroecosystems of Punjab and Haryana Region, India, A Synthesis

The Rice-Wheat cropping system (RWS) is the predominant agricultural system in northern India, especially in Punjab and Haryana. About 90% of agricultural land in Punjab and Haryana is indulged in the intensive RWS cropping system. The major constraint in this system is the short time interval between rice harvesting and the sowing of wheat. The preparation of the field for the wheat crop requires the removal of stubble, and farmers burn the stubble to get rid of it as there is a lack of any other proper management strategy or alternative use of stubble. Stubble burning is a significant source of pollutants causing severe damage to human health and the environment. The appropriate stubble management could provide immense economic benefits to the farmers and guard the environment against pollution. There is a dire need for alternative solutions to stubble burning. Some alternative management practices include the direct incorporation of the stubble into the soil, stubble as fuel, raw material for pulp and paper industries, or biomass for biofuel production. Since biochar is an effective tool for the utilization of stubble into a carbon-rich source, it can further be utilized in the agroecosystems because of its potential to improve soil fertility, enhance soil carbon, and reduce fertilizer use efficiency and enhance agricultural productivity. Thus, biochar, with its immense benefits, helps in soil conditioning and is an excellent means of carbon stabilization. The stable aromatic structure of carbon is resistant to chemical processes such as oxidation to CO2 or reduction to methane, making it a suitable means to act as a long-term carbon sink. We infer that biochar as an eco-friendly answer for this issue is an exceptionally viable soil conditioner that directly influences soil carbon, soil quality, crop production and food security, promoting economic and ecological benefits.

Profile Characteristics of the Farmers Showing Stubble Burning Behaviour in Punjab

Aim: To study the socio-personal, economic, communication, psychological, and situational characteristics of the farmers.&#x0D; Study Design: Descriptive design.&#x0D; Place and Duration of Study: Malwa region of Punjab, between first week of October 2019 to mid-December 2019.&#x0D; Methodology: Multi-stage sampling was followed. Malwa region was selected purposively because of the maximum number of stubble-burning incidents reported in the area during 2018. Within Malwa region, three districts (Bathinda, Sangrur and Ludhiana) were selected randomly. One block was selected randomly from each district and two villages were selected randomly from each selected block. The sample size of 246 was determined using Cochran’s formula and the selection of farmers was based on proportional allocation. Based on the literature, a total of 14 characteristics were taken to document the profile of the farmers who were engaged in the stubble burning behaviour.&#x0D; Results: The results indicated that most of the respondents were middle-aged (65.46%), male (91.06%), had formal education up to intermediate level (21.95%) and possessed semi-medium (5-10 acres) landholding (27.24%). Economic characteristics revealed that 51.46% farmers earned low annual income (&lt;Rs. 50,000- Rs.4,50,000), possessed lager milch animals (98.78%) and were practicing specialized farming (45.93%). More than half (51.63%) of the farmers possessed medium information seeking behaviour. Among psychological and situational characteristics, most of the farmers showed medium levels of innovativeness (49.19%), risk orientation (47.15%) and scientific orientation (57.32%) while high levels of ecological consciousness (45.53%) and economic motivation (42.28%). Most of the farmers (45.93%) showed medium level of awareness towards various stubble management measures.&#x0D; Conclusion: The analysis of these profile characteristics could be crucial in segmenting the farmer respondents and designing target-specific appropriate interventions to tackle the stubble burning behaviour of the farmers.

Effect of cultivation practices on diversity in susceptibility reactions of winter wheat genotypes to Fusarium head blight

Reports on the effectiveness of Fusarium head blight (FHB) control measures do not follow the same pattern in different regions, and the combined effects of abiotic and biotic factors on FHB are not fully understood. Consequently, the main objective of this study was to examine divergence in susceptibility reactions of winter wheat genotypes to FHB when exposed to the combined effects of cultivation practices, cultivar properties, year and the presence of interacting Fusarium spp. as an inherent whole. Analysed data originated from 633 grain samples collected from 434 localities in an eight-year period as a part of investigations related to the development of the DONcast® Europe prediction model. This study suggests that ploughing could increase the risk of the occurrence of less frequent toxigenic Fusarium species. Stubble management generated more divergent environmental factors than no-till farming, influencing greater variability in the relationship between deoxynivalenol (DON) accumulation and grain infection. The results of this study indicated differences in susceptibility reactions of varieties to FHB and suggested that more attention should be focused on the specificity of the interaction between variety and combined environmental stressors to ensure more predictive and sustainable wheat production.

Minimizing Lentil Harvest Loss through Improved Agronomic Practices in Sustainable Agro-Systems

Lentils are one of the most common legume crops used to diversify the cereal-oilseed cropping system in semi-arid environments. Lentils are a major source of protein and fiber for human consumption worldwide. However, the morphological characteristics of lentil plants—such as a short stem and low pod positioning—and complicated combine harvesting methods often result in yield loss. This also increases the susceptibility of a lentil crop to disease and render it less competitive against weeds. As a result, producers have resorted to using pesticides in order to mitigate the effects of weeds and disease. As a consequence, there have been undesirable negative environmental impacts on sustainable agroecosystems. Although land rolling, stubble management, and pesticide usage are common agronomic practices used to increase lentil yield and mitigate the issues associated with its morphology, their comprehensive effects on lentil growth and harvest loss are still not fully understood. In this study, we examined the impact of stubble management, the timing of land rolling, and the application of common fungicides and herbicides on lentil growth and yield. We found that stubble management and the timing of rolling modified lentil morphological structures, and thus impacted lentil yield and seed loss. These results were influenced by environmental factors, such as precipitation during the growing season. Although the results did not show significant interaction between fungicide application and lentil growth and yield, herbicide applications, stubble management, and the timing of rolling, along with common pesticide application strategies tested in our study, showed effects that were dependent on environmental conditions. Based on our results, we concluded that stubble management and the timing of rolling, combined with pesticide applications, can affect lentil seed loss and yield by modifying plant morphology. This was largely influenced by environmental conditions such as precipitation.

In-situ management of paddy stubble through microbial biodegradation

After the harvest of crop, the disposal of the rice stubbles remains a notable area of interest in all the growing areas of rice. The present review paper explores and highlights an effective strategy of decomposing the decomposers of the paddy stubble. Due to the increasing production of rice, there is an increase in rice crop residues and stubbles production. Conventional methods of management of paddy involve burning, surface retention, mulching, bailing, incorporation/amalgamation and direct removal. However, there are certain environmental challenges by using available agricultural implements. Thus, this current study demonstrates strategic management of the paddy crop residue for a sustainable environment. The developed eco-friendly methods will render new dimensions for the application of the post harvested residues. The review paper will be significant for sustainable management of the wastes of the paddy crop and hence strategic decomposition method, which will be beneficial for the society, farmers as well as the environment

The response of soil multi-functionality to agricultural management practices can be predicted by key soil abiotic and biotic properties

Soil organisms play an essential role in ecosystem functioning, including nutrient cycling and climate regulation. Most of soil functions have a microbial origin and recent findings suggest that various microbial community attributes (e.g. diversity, composition, abundance) are linked to the rate of soil functions in natural ecosystems. However, no such evidence is available from the agronomically managed systems. The types of agronomic practice and mechanisms (biotic vs. abiotic) that could impact microbial regulation of soil functions remain poorly understood. We collected soil samples from three long-term field trials across three geographically distinct regions with multiple management treatments (e.g. tillage, stubble management and fertiliser application) and measured the response of a number soil abiotic (e.g. soil aggregate stability, pH, nutrient status) and biotic (e.g. bacterial and fungal community structure, abundance of various microbial taxa) variables, and soil functions linked to nutrient cycling and nutrient availability. We used information theory and multi-model inference to identify key biotic and abiotic predictors of soil functions, and to model their response to land management through a multi-functionality index. Results indicated that no-till treatment generally impacted microbial community (42% decrease in the average gene copy number of all microbes compared to other management practices) and promoted soil structure (27% increase in the small aggregate fraction) but reduced some process rates, while stubble retention increased nutrient availability in the presence of fertilisation (59% on average). But these responses were site specific. The multi-functionality index associated with nutrient cycling declined under no-till system (47% on average) but increased when no-till was combined with stubble retention (49% on average) and fertiliser application (44%). Our modelling suggested that the best models that explained most of the variation in MF always included both abiotic and biotic variables. Amongst the latter, fungal community structure and beta(β)-Proteobacteria abundance were of importance as the model’s R² dropped by 12% when biotic attributes were removed providing evidence that the link between microbial community and soil functions was maintained in agricultural soils. This study provides support for the inclusion of microbial data in decision support systems for sustainable farming practices.

Additives as a Support Structure for Specific Biochemical Activity Boosts in Anaerobic Digestion: A Review

Anaerobic digestion is an attractive technology for resource management of organic waste and stubble. State of biochemical reactions and activities in anaerobic digestion determines the process stability. Biochemical activities such as syntrophic, metabolic, catalytic and enzymatic activities regulate the anaerobic efficiency for improved methane yield. Inhibitors such as accesses volatile fatty acids, ammonia, sulphur and heavy metals may slow down the anaerobic digestion and may cause reactor failure. However, additives for various biochemical activities may help to diminish the effect of inhibitors as well as improving process stability for enhanced methane yield. This manuscript presents an overview of various additives for enhancing the biochemical activities. The overview consists application of (a) conductive material for improving syntrophic activity, (b) trace metals for metabolic activities, (c) nanoparticles for improving catalytic activity, metabolism and symbiosis during AD, (d) biological additives for enzymatic action and (e) application of zeolite for introducing cation exchange property in anaerobic digestion. Also, comparison of various additives as per biochemical activity has also been performed for a deeper insight of application of additives in anaerobic digestion.

Soil carbon and nitrogen dynamics in a Vertisol following 50 years of no-tillage, crop stubble retention and nitrogen fertilization

Conservation agriculture commonly improves soil health and results in organic C sequestration. This study compared conventional tillage (CT) and no tillage (NT) systems, examining differences in stubble management [stubble burning (SB) and stubble retention (SR)] and N fertilization on soil C, C fractions and N. The experiment was established in 1968 on a Vertisol at Hermitage in Queensland, Australia. After 50 years of management; it was found that the tillage regime, the addition of N fertilizers, and the stubble management were all important in influencing soil C pools in 0–0.1 m of soil depth. Overall, the addition of N fertilizers and the tillage regime were the most important management factors. For example, the addition of N fertilizers at a rate of 90 kg ha−1 resulted in an average increase in SOC of 18%, while use of NT resulted in an average increase in SOC of 5%. Similarly, application of N fertilizers increased total soil N (TSN) concentrations by ≤25.5%, increased the stabilized SOC fraction by ≤26.6%, and increased microbial biomass C by ≤22%. Regardless, stubble management practices were also important, with the retention of stubble increasing TSN, increasing the stabilized C fraction, and increasing the microbial biomass C ≤ 30%. Finally, it was observed that the microbial metabolic quotient was 39% higher when stubble was burned and in the absence of N fertilization, indicating microbial stress under these treatments. The study clearly shows the importance of stubble retention and N fertilization in conservation agriculture for improvement in soil health and maintenance of soil C levels.

Bacterial and fungal diversity in rhizosphere and bulk soil under different long-term tillage and cereal/legume rotation

Soil microbial diversity is important in maintaining soil quality, sustainable agriculture, and ecosystem function. Soil management practices can influence the diversity and activity of soil microbes in agricultural fields. The objective of this study was to assess the effects of tillage and stubble management on the diversity of bacteria and fungi, chemical property and total carbon emission in the rhizosphere and bulk soils in wheat (Triticum aestivum L.) -pea (Pisum arvense L.) rotation at pre-harvest. Treatments included conventional tillage with stubble removed (T), no-tillage with stubble removed (NT), conventional tillage with stubble incorporated (TS), and no-tillage with stubble retained (NTS). Bacteria 16S rRNA (V3V4) and fungi ITS (ITS2) region genes were sequenced from bulk soil and rhizosphere soils. Abundance of the dominant bacterial (Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, and Planctomycetes) and fungal (Ascomycota and Basidiomycota) phyla identified did not differ significantly (P < 0.05) among treatments. Rhizobium and rare fungi Kurtzmanomyces occurred in the rhizosphere but were virtually absent in bulk soil. However, bacterial and fungal OTUs diversity indices were less in the rhizosphere compared to bulk soil. Soil from the NTS and NT had the greatest bacteria 16S rRNA and fungi ITS region number of OTUs; however, the microbial community did not differ among treatments. The abundance of class level bacteria and fungi were associated with soil pH, total organic carbon, total nitrogen, NH4+ -N, and NO3¯ -N contents. The results indicate that bulk soil had higher microbial library, which will be beneficial for establishment of the next season’s microbial community.

Cotton stubble effects on yield and nutrient assimilation in coastal saline soil

Stubble return is a proposed practice for soil amelioration and yield improvement. However, from the perspective of reducing soil salinity and improving soil nutrient availability, we have little knowledge of the effect of successive stubble return on cotton yield and nutrient uptake when cotton stubble is incorporated into saline field soil. Hence, a 5-year field study was conducted to investigate the effects of successive stubble management (stubble return and stubble removal) on lint yield and nutrient uptake of cotton, soil nutrients and salinity in the 0–80-cm soil profile. Stubble return increased lint yield by 22.7% and 47.3% in the fourth and fifth year, respectively, mainly through the production of more and larger bolls and the acquisition of more nutrients compared with stubble removal. 5-year cotton stubble return produced 20.0% more bolls and 7.7% larger bolls than stubble removal. Cotton plants accumulated 58.9% more nitrogen (N), 54.5% more phosphorus (P), and 48.2% more potassium (K) under stubble return than stubble removal during the last two years of the experiment. Stubble return increased internal N use efficiency (iNUE) and internal K use efficiency (iKUE) at the fourth or fifth year compared with stubble removal, without influence on internal P use efficiency (iPUE). Stubble return decreased soil pH and salinity in the 0–40-cm soil layer in the fourth and fifth year. The soil nitrate content below the 40-cm soil layer was reduced, while the nitrate concentration in the 0–20-cm soil layer increased after 4 years of stubble return. Available K in the 0–40-cm soil layer increased, while available P in the 0–20-cm soil layer was reduced after 5 years of stubble return. Our analyses demonstrate that cotton stubble return has the potential to improve cotton yield and may be an effective practice to apply in coastal saline areas.

Improving the productivity and stability of oilseed cropping systems through crop diversification

Diversifying cropping systems is essential to enhance oilseed production resiliency in a changing climate. Here, we determined the productivity and stability of five oilseed crops under different crop stubble management strategies over all nine environments. A 2-year cropping sequence study was conducted at nine environ-sites (3 sites×3 independent 2-yr cropping sequence phases). Crops in year 1 consisted of chemical fallow, lentil (Lens culinaris L.) and spring wheat (Triticum aestivum L.), which resulted in fallow, lentil and wheat stubbles for the following year crops. Crops in year 2 were five oilseed crops: canola (Brassica napus L.), Ethiopian mustard (Brassica carinata L.), oriental mustard (Brassica juncea L.), yellow mustard (Sinapis alba L.), and camelina (Camelina sativa L.). Over all nine environ-sites, B. juncea had high yield and low yield variation, making it a good substitute for B. napus, the primary oilseed crop in acreage on the Canadian Prairies. Lentil and wheat stubbles reduced oilseed crop yields by 4% and 5% compared with chemical fallow, respectively; however, at the 2-yr cropping sequence level, lentil-oilseed sequence increased system production, expressed by annualized canola equivalent yield, by 33% compared with wheat–oilseed sequence and by 112% compared with fallow–oilseed system. The lentil-oilseed sequence had the lowest variation in production and was most suitable for high-yielding environments compared with fallow- and wheat–oilseed sequences, while B. juncea- and B. napus-based cropping sequences were most stable based on the static and dynamic stabilities among all five oilseed-based cropping sequences. Crops explained more variation in system production than weather (40% vs 5%) because of a dramatic difference of cropping sequences with and without fallow. Under changing climatic conditions, diversifying conventional wheat- or fallow-based canola systems using lentil and B. juncea will enhance system productivity and yield stability across different environments.

Weed growth, herbicide efficacy, and rice productivity in dry seeded paddy field under different wheat stubble management methods

To ascertain the influence of wheat stubble management options and chemical weed control methods on weed growth and productivity of dry direct-seeded fine rice, a two years' field study was undertaken at the Agronomic Research Farm, University of Agriculture, Faisalabad, Pakistan in 2013 and 2014. Different wheat stubble management methods, viz., incorporation, burning and retention were executed during seed-bed preparation. While, herbicide treatments comprised of a weed check, weed free, pendimethalin followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl, and bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl. Results revealed that weed control efficacy of both herbicide treatments ranged from 84 to 94%. Herbicide treatments significantly reduced weed density (88–90%) and dry weight (86–88%), while improved the rice growth attributes compared with weed check. Application of bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention recorded 226 and 273% increase in kernel yield over weedy check in 2013 and 2014, respectively. In stubble incorporation, pendimethalin followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl was more effective in increasing (256–293%) rice yields over weedy check. Among different treatment combinations, the maximum net benefits (1397.49–1472.22 USD ha−1), net returns (636–700 USD ha−1), benefit cost ratio (1.77–1.83) and marginal rate of return (2187–2330%) were recorded with the application of bispyribac sodium followed by fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention. In crux, application of bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention is efficient approach to control weeds, and get maximum rice productivity and net economic returns under dry seeded system.