Combination Of Management Practices Research Articles

Integrating seasonal forecast information with crop models to inform decision making in small-scale farming under climate variability

Integrating seasonal forecast information and crop models has the potential to inform farm management decisions under climate variability. The study assessed the feasibility of integrating seasonal forecast information into crop models for decision making in small-scale farming conditions in South Africa. Seasonal forecast outputs from the GCM, CFSv2, were coupled into the DSSAT v4.7 crop model to evaluate the impact of farm management decisions in Limpopo, South Africa. Historical weather and seasonal forecast data for the 2011–2017 and 2017/2018 seasons were utilised to set up and validate decision scenarios. The analysis of maize yield data under different combinations of management practices and seasonal forecasts yielded a range of decision scenarios. Overall, there were no notable differences in farm management decision scenarios among different farmer types. Integrating seasonal forecast information into crop models offers valuable insights in cases where decision capacity is low and climate sensitivity is high, as well as where decision capacity is high and climate sensitivity is weak. The decision support system proved more effective for cereal and vegetable crops than for legumes. In conclusion, integrating seasonal forecast information into crop models is a feasible approach for enhancing farm management decision making in South African small-scale farming systems.

A fuzzy logic evaluation of synergies and trade-offs between agricultural production and climate change mitigation

This study introduces a trade-off evaluation system, the Σommit index, which considers four components: crop yield, soil carbon stock changes, direct and indirect nitrous oxide emissions, and nitrate-nitrogen leaching across alternative agronomic case scenarios, i.e., combinations of management practices within specific pedo-climatic conditions. The four trade-off components have been estimated by combining standard equations and emission factors from the Guidelines for National Greenhouse Gas Inventories, complemented with Grey Water Footprint accounting Guidelines and other meta-analyses. The Σommit index has been developed using a harmonised dataset of ∼1.8 million agronomic case scenarios, leveraging fuzzy logic to aggregate the trade-off components into a value ranging from 0 (bad) to 1 (good). It has been tested under three narratives reflecting stakeholders' sustainability priorities (young farmers, agrochemical companies, EU Common Agricultural Policy paying agency), using alternative weighting schemes derived from expert opinion. Adding organic matter input, intermediate N fertilisation (50–150 kg ha−1), no-tillage, winter cereal cultivation, and irrigation for summer cereals have consistently achieved higher performance across all narratives. When assigning a higher weight to soil carbon stock changes, a broader range of Σommit index values emerged, while assigning higher importance to crop yield has led to a narrower evaluation. We openly release the dataset of agronomic case scenarios, along with the scripts to replicate the methodology and an interactive dashboard to inspect the results. These resources are meant to be used by different stakeholders (e.g., policymakers, Common Agricultural Policy payment agencies, farms, agrochemical industry) as a complement to the Intergovernmental Panel on Climate Change methodology to improve current understanding and awareness of environmental trade-offs and synergies in agricultural management.

Deciphering the Interactions in the Root–Soil Nexus Caused by Urease and Nitrification Inhibitors: A Review

Optimizing nitrogen (N) availability to plants is crucial for achieving maximum crop yield and quality. However, ensuring the appropriate supply of N to crops is challenging due to the various pathways through which N can be lost, such as ammonia (NH3) volatilization, nitrous oxide emissions, denitrification, nitrate (NO3−) leaching, and runoff. Additionally, N can become immobilized by soil minerals when ammonium (NH4+) gets trapped in the interlayers of clay minerals. Although synchronizing N availability with plant uptake could potentially reduce N loss, this approach is hindered by the fact that N loss from crop fields is typically influenced by a combination of management practices (which can be controlled) and weather dynamics, particularly precipitation, temperature fluctuations, and wind (which are beyond our control). In recent years, the use of urease and nitrification inhibitors has emerged as a strategy to temporarily delay the microbiological transformations of N-based fertilizers, thereby synchronizing N availability with plant uptake and mitigating N loss. Urease inhibitors slow down the hydrolysis of urea to NH4+ and reduce nitrogen loss through NH3 volatilization. Nitrification inhibitors temporarily inhibit soil bacteria (Nitrosomonas spp.) that convert NH4+ to nitrite (NO2−), thereby slowing down the first and rate-determining step of the nitrification process and reducing nitrogen loss as NO3− or through denitrification. This review aims to provide a comprehensive understanding of urease and nitrification inhibitor technologies and their profound implications for plants and root nitrogen uptake. It underscores the critical need to develop design principles for inhibitors with enhanced efficiency, highlighting their potential to revolutionize agricultural practices. Furthermore, this review offers valuable insights into future directions for inhibitor usage and emphasizes the essential traits that superior inhibitors should possess, thereby paving the way for innovative advancements in optimizing nitrogen management and ensuring sustainable crop production.

Simulation of water drainage and nitrate leaching at an irrigated maize (Zea mays L.) oasis cropland with a shallow groundwater table

Nitrogen pollution is a serious threat to water resources worldwide, and it poses a particular threat to groundwater in desert oases where the water table is shallow. Leaching loss of nitrogen fertilizer means economic loss and threatens the water quality of phreatic aquifer with a thinner vadose zone thickness, especially in the Hailiutu River catchment, China, where phreatic aquifer is a unique source of local domestic water. The objective of this study was to quantify N leaching for irrigated maize with different fertilizer and irrigation management practices, as well as fluctuating groundwater tables, and to recommend the best management practices for maize. A field experiment was conducted in such a locale for two consecutive years. Maize was grown where nitrogen was introduced at increasing rates (from 38 to 438 kg N ha−1, at intervals of 100 kg N ha−1). The 338 kg N ha−1 represented the conventional fertilization practice (N338), and served as a reference. Unlike the conventional 70 mm irrigation depth applied at each water application, water conserving irrigation was performed by applying only 20 mm at each irrigation — six times in 2017 and four in 2018. The HYDRUS-1D model was first calibrated against measured soil moisture and nitrate in soil water across all soil layers, then independently validated and finally repeatedly run to simulate NO3N leaching under the following simulation conditions: a) increasing N fertilization rate, but fixed 20 mm individual irrigation depth; b) increasing individual irrigation depth (from 10 to 70 mm), but only considering the reference N fertilization rate (N338). In both cases, five different shifts in water table depth were assumed, + 0.10, 0, − 0.10, − 0.20, or − 0.30 m of groundwater table change, respectively. The simulation results suggest that conventional fertilization practices result in nitrogen losses of over 100 kg ha−1, and 238 kg N ha−1 N fertilization, accompanying by a depth of 20 mm for each irrigation is the best combination of management practices. The NO3−N leaching loss was more influenced by the depth of irrigation than the fertilizer application rate. A shallower water table resulted in the greater loss of NO3N by leaching. Such results can help develop improved irrigation and nitrogen fertilization management for desert oasis cropping systems.

Usage and Impacts of Technologies and Management Practices in Ethiopian Smallholder Maize Production

Maize yields can be improved through many individual technologies and management practices, but the full realization of potential benefits is generally understood to require integrated use of complementary practices. We employed two years of survey data and alternative econometric models to better understand the use of individual and bundled packages of technologies and management practices in Ethiopian maize production, i.e., fertilizers, improved varieties, herbicides, pesticides, manure, intercropping, erosion control and crop rotation (the last three labeled integrated management). Although fertilizer and improved varieties were used on 85% of maize fields, with average yields of 3.4 ton/ha, large yield gaps remain. Complementary management practices improved these yields by as much as 22%, although in variable ways. Integrated management contributed to maize yield only when combined with crop protection (herbicides and/or pesticides). Combining manure with fertilizer and improved variety decreased maize yields, possibly due to manure quality and less inorganic fertilizer used on fields that received manure. Packages including crop protection increased labor productivity by 16–70%, while using integrated management decreased labor productivity by almost half. In summary, the combination of management practices did not automatically lead to increased yields, partly related to the conditions under which practices were applied, indicating the need for site-specific research and recommendations for sustainable intensification.

Balancing openness and control to improve the performance of crowdsourcing contests for product innovation: A configurational perspective

This study inductively explores the interplay between openness and control and their impact on the performance of crowdsourcing contests for product innovation. Building on an analysis of crowdsourcing literature, we conceptualize openness and control in terms of six management practices: rewards, feedback, community building, access restrictions, task instructions and evaluation rights. For greater clarity on the units of analysis, an explicit distinction is made between different contextual settings in terms of the locus of innovation, i.e., core or peripheral subsystem innovation. A sample of 159 crowdsourcing contests for consumer electronics innovation is analyzed through a configurational approach, which identifies four high-performing solutions. The results indicate that openness and control are deeply interrelated and their appropriate combination may depend on the locus of innovation. Propositions associated with the openness/control issue of crowdsourcing contests are developed according to the results. The findings provide integrative insights into how particular combinations of management practices can help strike the right balance between openness and control in crowdsourcing contests.

Phenotypic Traits, Grain Yield and Yield Components of Maize Cultivars Under Combinations of Management Practices in Semi-arid Conditions of Iran

In semi-arid regions, selecting cultivars and planning management practices are critical issues for improving yields and reducing risks of maize cultivation in the short summer cropping season. This study aimed to assess the responses of grain yield (GY) and important phenotypic characteristics of maize cultivars from different maturity groups under various irrigation regimes, planting dates, and nitrogen rates, in a 2-year experiment. According to the clusters identified in the loading plot, stover yield, radiation use efficiency (RUE), height, leaf greenness index, stem weight, and ear size during flowering (VT/R1) were strongly correlated with GY, yield components and harvest index. Based on analysis of variance, more irrigation or N, or their interaction often increased GY, rows ear−1, grains row−1 and hundred-grain weight. Late planting decreased GY of KSC704 (late maturity cultivar). KSC260 (early maturity cultivar) had greater flexibility in planting time, required less days for maturity, and had less water consumption. The findings highlight the physiological basis of the relationship between the different phenotypic characteristics and how they affect GY and its components. They were in line with the established theories that higher RUE, biomass and sink activity (e.g. grain weight and numbers, and larger ear size) are associated with better genetic gains to produce high GY. Although the results were not consistent between years, findings suggested the good performance of recently released early maturity cultivars for use during the summer growing season.

Environmental and social consequences of the increase in the demand for ‘superfoods’ world‐wide

Abstract The search for healthy diets has led to a surge in the demand for functional foods or ‘superfoods’, which have now become popular among the middle‐ and high‐income fractions of the society in developed regions of the world. ‘Superfoods’ are predominantly consumed far from their centres of origin and out of their cultural context with different environmental and social effects. Here, we present a series of case studies to provide an overview of the different environmental impacts driven by superfood expansion. We show that if these crops are to follow the path of other global commodities, then strong environmental impacts and large carbon footprints are expected in terms of land clearing, use of agrochemicals and transportation during times of high prices (boom) and social problems as farmers have to abandon their livelihoods when prices sink below the cost of production (bust). We also showcase how a combination of management practices, consumer choices and policy changes could help in alleviating the ecological footprint of these crops. A free Plain Language Summary can be found within the Supporting Information of this article.

Crop intensification with sustainable practices did not increase N2O emissions

Nitrous oxide (N2O) is the most important greenhouse gas produced by agricultural soils and is a byproduct of microbial nitrification and denitrification processes. The N2O emission rates depend on soil, climatic and management factors. The objectives of this study were i) to evaluate N2O emissions during a barley crop period and its subsequent barley-maize interperiod, under two management systems, and ii) to relate the N2O flux rates with soil mineral N content, waterfilled pore space (WFPS) and soil temperature. These periods are part of three-year crop sequence (barley - maize - soybean) of a long-term experiment under two management systems, ecological intensification (EI) and farmer current practices (FP). For the analyzed period, the EI system included a cover crop after barley and higher N rates, with split application, compared to FP. N2O emissions were monitored weekly using a static chambers method. Simultaneously, the mineral N content (NO3--N and NH4+-N), WFPS and soil temperature at 10 cm depth were determined. The flux of N2O-N ranged from 6 to 61 μg of N2O-N m2 h-1 during the barley crop and between 1.5 and 47 μg of N2O-N m2 h-1 during the barley-maize interperiod, without significant differences between management systems. N2O emissions were controlled by soil temperature and %WFPS according to a multiple regression analysis. NH4+-N and NO3--N soil content did not enter into any model as a regulator of N2O flux. During the barley period there was a significant effect of the WFPS × soil temperature interaction since N2O emissions increased with soil temperature only at WFPS > 40 %. During the barley-maize interperiod, there were significant positive effects of WFPS and temperature on N2O emissions with no significant WFPS x temperature interaction. The cumulative emissions of N2O-N were not different between management systems during the barley crop (IE = 646 and FP=757 g N2O-N ha-1) or during barley-maize interperiod (IE = 816 and FP=754 g N2O-N ha-1). Throughout the study period, the combination of management practices in EI increased barley yield and did not increase N2O emissions with respect to FP, despite higher N rates and the inclusion of cover crop in EI. The intensification of crops does not necessarily increase N2O emissions from agricultural soils as long as the crops are conducted with appropriate management practices.

Effects of interactions between feeding practices, animal health and farm infrastructure on technical, economic and environmental performances of a pig-fattening unit

European pig production faces economic and environmental challenges. Modelling can help farmers simulate and understand how changes in their management practices affect the efficiency of their production system. We developed an individual-based model of a pig-fattening unit that considers individual variability in performance among pigs, farmers’ feeding practices and animal management and estimates environmental impacts (using life cycle assessment) and economic results of the unit. We previously demonstrated that this model provides reliable estimates of farm performance for different combinations of management practices, pig types and building characteristics. The objectives of this study were to quantify how interactions between feeding practices and animal management influence fattening unit results in healthy or impaired health conditions using the model. A virtual experiment was designed to evaluate effects of interactions between feeding practices, health status of the pig herd and infrastructure constraints on the technical performance, economic results and environmental impacts of the unit. The virtual experiment consisted of 96 scenarios, which combined chosen values of 6 input parameters of the model: batch interval (35 days and 7 days), use or non-use of a buffer room to manage the lightest pigs, feed rationing (ad libitum and restricted) and sequence plans (two-phase (2P), daily-phase (DP)), scale at which the feeding plan is applied (i.e. room, pen and individual) and health status of the pig herd (i.e. healthy v. impaired). Variance analysis was used to test effects of the factors in these 96 scenarios, and multivariate data analyses were used to classify the scenarios. Healthy populations obtained on average higher economic results (e.g. gross margin of 11.20 v. 1.50 €/pig) and lower environmental impacts (e.g. 2.24 v. 2.38 kg CO2-eq/kg pig live weight gain) than the population with impaired health. With 35 days batch interval and DP feeding, populations with impaired health reached gross margin similar to healthy populations with 2P ad libitum feeding and 7 days batch interval. Restricted, DP and individual feeding plans improved the economic and environmental performances of the unit for both health statuses. This study highlighted that health status of the pig herd is the main factor that affects technical, economic and environmental performances of a pig-fattening unit, and that adequate feeding strategies and animal management can compensate, to some extent, the effects of impaired health on environmental impacts but not on gross margin.

Deforestation and current management practices reduce soil organic carbon in the semi-arid Chaco, Argentina

The soil is a fundamental component of the C cycle. Land use changes can alter the soil organic carbon (SOC) content, a key determinant of several regulation ecosystem services. Here, we analyzed the effects of land cover (e.g. from forest to cropland) and land use (i.e. management practices) change on SOC in the semi-arid Chaco of Argentina, a global deforestation hotspot. Using the CENTURY model, we analyzed SOC changes over 20 years for two sites with contrasting rainfall (600 and 800 mm). For each site, we evaluated the effect of different combination of management practices (e.g. fertilization, grazing intensity) and land uses (i.e. annual crops and sown pastures). 98.5% of the simulations performed for cropping systems showed a reduction in SOC, with an average reduction of 25% respect to the native forest. Wheat proportion in the crop rotation had the highest relative influence on SOC variation (54%), higher than the proportion of maize (26.4%) and nitrogen fertilization (9.8%). For sown pastures, <40% of the simulations showed SOC decreases up to 18%. Grazing intensity had the greatest relative influence on SOC variation in both sites (>60%), followed by burning (19%), temporary exclusion of cattle (12%) and nitrogen fertilization (4.3%). In most cases SOC changes were mainly explained by changes in C inputs (i.e. NPP) rather than by changes in outputs (i.e. respiration and erosion). Therefore, delta SOC showed a strong negative relationship with the Human Appropriation of NPP (R2 = 0.54 and 0.67 in cropping systems and pastures, respectively). Overall, our results suggest that land use change has negative effects on SOC regardless of the management practices implemented. The few combinations that balanced food production and carbon sequestration were maize monocultures with annual N fertilization, and cattle raising with temporary exclusion and burning suppression. Our results may be used to define management practices that allow maintaining soil carbon stocks in the upper soil layer.

Water Quality Management of a Cold Climate Region Watershed in Changing Climate

Cold climate regions provide a multitude of ecosystem services. However, cold regions under a changing climate could be more vulnerable than others because their glaciers, freezing soils and peatlands are sensitive to the slightest of changes in climate. This has posed serious threats to the water resources, sustainable goods production and ecosystem services that depend on regional water quality. Therefore, proper watershed management is imperative. In this paper, we investigate this issue in a cold climate watershed in central Alberta, Canada with the main objective of quantifying the impacts of climate change on water quality status. We modified specific water quality related processes of a process-based model – Soil and Water Assessment Tool (SWAT) with a view of better representing the reality of cold climate regions. A SWAT model is then built-up, followed up by a multi-site and multi-objective (streamflow, sediment and water quality) calibration, validation and uncertainty analysis in a baseline period (1983 - 2013). The calibrated and validated model is then fed with a high spatial resolution (25 km) daily future climate data – the CanRCM4. Improvements on stream water temperature (Ts) and dissolved oxygen (DO) simulations justified the modifications. This model is able to simulate the dynamics of other water quality variables (carbonaceous biochemical oxygen demand – cBOD, total nitrogen – TN and phosphorus – TP) with a wide range of accuracy (very good to satisfactory) in the base period. Agriculture areas account for the highest amount of annual TN (11.16 kgN/ha) and TP (2.88 kgP/ha) yield rate in the base period leading to poor water quality status in the immediate downstream reaches. The situation would be further exacerbated (16.52 kgN/ha and 4.89 kgP/ha) in future. Finally, we tested different alternative management options to compare the water quality status of the Athabasca River Basin (ARB) under a changing climate. Significant reduction in future nutrient concentrations (~ 20% on TN and 60% on TP) can be achieved using a certain combination of management practices and the ecological status of the basin can be improved. This demonstrates that the modified SWAT model can be applied to other cold climate regions, and that the results can be translated to help in managing the ARB in a more holistic way.

Impact of projected climate on wheat yield in India and its adaptation strategies

Wheat is highly sensitive to climate change especially temperature changes experienced in the later phase of crop season. Hence, it is of immense importance to know how and to what extent climate change will affect wheat yields and to assess the adaptive strategies for mitigating possible negative consequences on wheat production. Wheat yield responses to three future climatic periods (2025, 2050 and 2075) were studied by driving DSSAT-Wheat (v4.5) model with daily weather from three CMIP-5 climate models’ (GFDL-ESM2M, MIROC5, and NorESM1-M) as the basic input at four sites (Ludhiana, Raipur, Akola and New Delhi) representing three major wheat growing zones of the country. Projected changes in growing season (November-March) day and night temperatures at four sites differed substantially both in direction and magnitude. Day temperatures are projected to rise conspicuously at Ludhiana, representing northwest parts of the country, and moderately over central parts of India (Akola and Raipur). Positive rainfall anomalies at Ludhiana (+76%) and negative anomalies at Raipur (-15%) are projected in future climates. With these anticipated changes, wheat is likely to experience warmer days (+1.1 °C) at Ludhiana and nights at Raipur (+2.8 °C) and more seasonal moisture availability at Ludhiana in future climates. Negative impacts of climatic change in these sites are found to be minimized by adapting one or a combination of management practices, which are site specific.

Agronomic and physiological aspects of nitrogen use efficiency in conventional and organic cereal-based production systems

AbstractBetter management of synthetic nitrogen (N) fertilizers in conventional agricultural systems laid the foundation for feeding the increasing world's population since the Green Revolution. However, excessive reliance on inorganic fertilizer has resulted in environmental degradation issues. Difficulties in soil nutrition management in organic cropping systems often results in lower and variable yields, also raising questions of sustainability. Improving nitrogen use efficiency (NUE) is thus of key importance to overcome environmental concerns in conventional systems and production limitations in organic systems. The differences in the two farming systems have impacts on crop traits and N cycles, making it difficult to enhance NUE with a single strategy. Different approaches need to be adopted to improve NUE in each system. Extensive efforts have been made to better understand mechanisms to potentially improve NUE in cereal crops under both systems. This review suggests that NUE may be improved through a combination of management practices and breeding strategies specific to the management system. Diversified crop rotations with legumes are effective practices to optimize the N cycle in both conventional and organic systems. Best Management Practices coupled with nitrification inhibitors, controlled release products and split-application practices can reduce N loss in conventional systems. In organic systems, we need to take advantage of available N sources and adapt practices such as no-tillage, cover crops, and catch crops. Utilization of beneficial soil microorganisms is fundamental to optimizing availability of soil N. Estimation of soil organic matter mineralization using prediction models may be useful to enhance NUE if models are calibrated for target environments. Cereal crops are often bred under optimum N conditions and may not perform well under low N conditions. Thus, breeders can integrate genetic and phenotypic information to develop cultivars adapted to specific environments and cultivation practices. The proper choice and integration of strategies can synchronize N demand and supply within a system, resulting in reduced risk of N loss while improving NUE in both conventional and organic systems.

Survey of reproduction management on Canadian dairy farms.

The objectives of this study were to (1) quantify current reproduction management practices, and (2) assess the association between these practices and herd reproductive performance on dairy farms in Canada. A bilingual survey was developed, validated, and administered from March to May 2014 to collect general and reproduction management and performance measures [annual 21-d pregnancy rate (PR), 21-d insemination rate (IR), and conception risk (CR)]. Associations between management practices and reproductive performance measures were tested using linear regression models. A total of 832 questionnaires were completed online and by mail, representing a response rate of 9%. On average, farms had 77 lactating cows (median=50) and 13 dry cows (median=10), and Holstein was the most common breed (92% of herds). Lactating cow housing was tiestall on 61% of the farms, freestall on 37%, and bedded pack on 2%. The average voluntary waiting period was 58 d in milk (DIM). The main reproduction management practice per farm was defined as the means employed for >50% of inseminations. Farms reported their main reproduction management practice for first and subsequent inseminations, respectively, as visual estrus detection (51 and 44% of herds), timed AI (21 and 23% of herds), automated activity monitoring (AAM; 10 and 10% of herds), other management practice (bulls; 2 and 2% of herds), and a combination of management practices (16 and 21% of herds). On farms using visual estrus detection, cows were observed for signs of estrus on average 3.5 times per day, for an average total of 36 min/d. The most common use of reproductive hormones was to synchronize ovulation using Ovsynch (58% of the farms). Average PR, IR, and CR were 17.6, 44.1, and 40.5%, respectively. In linear regression analyses adjusted for confounders, pregnancy rate was significantly associated with geographic region, housing (tiestall: PR=15.4%, freestall: PR=17.6%), herd size (<50 lactating cows: PR=16.2%, 50-100 cows: PR=16.5%, >100 cows: PR=17.8%), voluntary waiting period (≤60 DIM: PR=17.6%, >60 DIM: PR=15.9%), and frequency of insemination per day (once daily: PR=16.6%, twice or more daily: PR=18.1%). The main reproduction management practice at first and subsequent inseminations was divergently associated with IR and CR, but not with PR (visual heat detection: PR=17.4%, timed AI: PR=18.4%, AAM: PR=17.1%, combined practices: PR=18.2%).

Learning from commercial crop performance: Oil palm yield response to management under well-defined growing conditions

Farmers learn from their own experiences. However, they are rarely sure if an exceptionally good or bad outcome is due to chance effects or whether it is due to a given combination of management practices and environmental conditions. We surmised that, if each harvest event is adequately characterized and a large number of these events are analyzed together, it should be possible to associate crop response to management within a particular set of growth conditions. We tested this hypothesis using the perennial crop, oil palm.The characterization of the harvest events can be divided into factors the grower can control (CFs), and non-controllable factors (NCFs). Expert opinion, coupled with literature reviews, indicated that the most important NCFs for oil palm in the humid tropics were surplus water and water deficits in the three-year period before and including the year of harvest. Water deficit was assessed using a simplified water balance model with inputs on inherent soil characteristics and rainfall. Surplus water was evaluated from the rainfall, inherent soil characteristics and the topographical position of the block in question. Homologous events (HEs) with similar NCFs were determined from weather and soil data for 141 blocks covering >6000ha over the period 2007–2013 on a commercial plantation.The yield of fresh fruit bunches (FFB) of 262 blocks over the period 2009–2013 was analyzed on the conceptual basis that if HEs can be defined in terms of growing conditions and used to account for part of the yield variation (NCFs), then the remaining variation within these events can be attributable to controllable factors (CFs) or management practices. Inclusion of HEs for the three years before the harvest year improved models used to explain yield variation. The variations in yield were in accordance with the expected effects of the distinct HEs confirming their validity as an analytical tool with normal conditions giving the highest yields, either deficit or surplus water giving intermediate yields, and a combination of both deficit and excess water the lowest yields.We chose the CF of fertilizer response to associate variation of management practices and yield within and across HEs. The overall response to fertilizer at 12.8kgFFB·kg−1, without including HEs in the model, was much greater than that obtained when HEs were included (5.9kgFFB·kg−1). As most data were from blocks with sup-optimal growing conditions, the response to fertilizer over the ranges used was small and under the poorest HEs was not detectable.

Banded Leaf and Sheath Blight of Maize: Historical Perspectives, Current Status and Future Directions

Rhizoctonia solani f. sp. sasakii causing banded leaf and sheath blight disease is one of the important pathogens of maize. It has rapidly gained economic importance in several parts of world and has potential to inflict economic loss up to 100 %. The disease, which is more prevalent in humid weather with temperature of around 28 °C, poses challenge to maize growers due to its soil borne nature and lack of resistant cultivars. The disease is difficult to control through either fungicides or crop rotation alone. Inheritance studies have indicated digenic and oligogenic nature of disease resistance. Quantitative trait loci controlling banded leaf and sheath blight have recently been identified that would facilitate the development of maize hybrids resistant to this disease. Therefore, a combination of management practices is required for control of banded leaf and sheath blight. The present paper reviews the available information on various aspects such as distribution, yield loss, symptoms, pathogen life cycle, epidemiology, creation of artificial disease epiphytotics and its integrated management through cultural, biological, chemical and genetic means. The consolidated knowledge presented in this review should help better disease management and reduce crop loss due to banded leaf and sheath blight.

Chronic nitrogen fertilization and carbon sequestration in grassland soils: evidence of a microbial enzyme link

Chronic nitrogen (N) fertilization can greatly affect soil carbon (C) sequestration by altering biochemical interactions between plant detritus and soil microbes. In lignin-rich forest soils, chronic N additions tend to increase soil C content partly by decreasing the activity of lignin-degrading enzymes. In cellulose-rich grassland soils it is not clear whether cellulose-degrading enzymes are also inhibited by N additions and what consequences this might have on changes in soil C content. Here we address whether chronic N fertilization has affected (1) the C content of light versus heavier soil fractions, and (2) the activity of four extracellular enzymes including the C-acquiring enzyme β-1,4-glucosidase (BG; necessary for cellulose hydrolysis). We found that 19 years of chronic N-only addition to permanent grassland have significantly increased soil C sequestration in heavy but not in light soil density fractions, and this C accrual was associated with a significant increase (and not decrease) of BG activity. Chronic N fertilization may increase BG activity because greater N availability reduces root C:N ratios thus increasing microbial demand for C, which is met by C inputs from enhanced root C pools in N-only fertilized soils. However, BG activity and total root mass strongly decreased in high pH soils under the application of lime (i.e. CaCO3), which reduced the ability of these organo-mineral soils to gain more C per units of N added. Our study is the first to show a potential ‘enzyme link’ between (1) long-term additions of inorganic N to grassland soils, and (2) the greater C content of organo-mineral soil fractions. Our new hypothesis is that the ‘enzyme link’ occurs because (a) BG activity is stimulated by increased microbial C demand relative to N under chronic fertilization, and (b) increased BG activity causes more C from roots and from microbial metabolites to accumulate and stabilize into organo-mineral C fractions. We suggest that any combination of management practices that can influence the BG ‘enzyme link’ will have far reaching implications for long-term C sequestration in grassland soils.

Land management trumps the effects of climate change and elevated CO2 on grassland functioning

Summary Grasslands cover ˜30% of the Earth's terrestrial surface and provide many ecosystem services. Many grasslands are heavily managed to maximize these services for human benefit, but the outcome of management is anticipated to be increasingly influenced by various aspects of climate change and elevated atmospheric CO2. The relative importance of global change vs. land management on grasslands is largely unknown. A meta‐analysis is used here to examine drivers at both scales primarily targeting services provided by grasslands relating to plant productivity (above‐ and below‐ground biomass) and soil processes (nutrients and soil respiration) in 38 manipulative experiments published in the last decade. We specifically target effects of (i) single and combined land management practices (LMs), (ii) single and combined factors relating to broad‐scale climate change and elevated CO2, and (iii) combined management practices and changes to climate and CO2. Collectively, this examines the general efficacy of global change models in predicting changes to grassland functioning. We found that combinations of management practices had approximately double the explanatory power for variation in grassland services compared with individual or interactive effects of factors associated with climate change and CO2. These interacting management practices such as nutrient additions and defoliation predominantly influenced functions associated with productivity or biomass both below and above ground. The effects of interacting factors of climate and CO2 influenced a wider range of ecosystem functions, but the magnitude of these effects was relatively smaller. Interactions between management practices or between climate change/CO2 factors always had higher explanatory power than any factor in isolation indicating that multivariate synergistic models of environmental change can better describe impacts on ecosystem function in plant communities (e.g. relative to univariate climate‐based models). Given that the magnitude and direction (positive or negative) of the interactions varied widely, this also implies that the outcomes of these multivariate interactions can vary spatially, temporally or by immediate context (e.g. management prescriptions). Synthesis. Although our work confirms how climate change and CO2 can affect many ecosystem‐based functional attributes, it suggests that combinations of LMs remain the dominant set of factors in determining the performance of grassland plant communities. Land management may thus be critical for influencing projected responses to future climate change and elevated CO2 in models of grassland function at least for factors relating to primary production.

Animal Health and Welfare Issues Facing Organic Production Systems.

Simple SummaryThe demand for organically grown, animal derived produce is increasing due to a growing desire for consumer products that have minimal chemical inputs and high animal welfare standards. Evaluation of the scientific literature suggests that a major challenge facing organic animal production systems is the management and treatment of health-related issues. However, implementation of effective management practices can help organic animal producers achieve and maintain high standards of health and welfare, which is necessary to assure consumers that organic animal-based food and fibre has not only been produced with minimal or no chemical input, but under high standards of animal welfare.The demand for organically-grown produce is increasing worldwide, with one of the drivers being an expectation among consumers that animals have been farmed to a high standard of animal welfare. This review evaluates whether this expectation is in fact being met, by describing the current level of science-based knowledge of animal health and welfare in organic systems. The primary welfare risk in organic production systems appears to be related to animal health. Organic farms use a combination of management practices, alternative and complementary remedies and convenional medicines to manage the health of their animals and in many cases these are at least as effective as management practices employed by non-organic producers. However, in contrast to non-organic systems, there is still a lack of scientifically evaluated, organically acceptable therapeutic treatments that organic animal producers can use when current management practices are not sufficient to maintain the health of their animals. The development of such treatments are necessary to assure consumers that organic animal-based food and fibre has not only been produced with minimal or no chemical input, but under high standards of animal welfare.