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Jun 2022, Volume 9 Issue 2
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    Wen-Feng CONG, Hans LAMBERS, Fusuo ZHANG
    Hans LAMBERS, Wen-Feng CONG

    ● For 8000 years, agricultural practices have affected atmospheric CO2 concentrations.

    ● Paddy rice cultivation has impacted atmospheric CH4 concentration since 5000 years ago.

    ● Modern agricultural practices must include carbon storage and reduced emissions.

    ● Sustainable management in agriculture must be combined with decarbonizing the economy and reducing population growth.

    Since humans started practicing agriculture at the expense of natural forests, 8000 years ago, they have affected atmospheric CO2 concentrations. Their impact on atmospheric CH4 started about 5000 years ago, as result of the cultivation of paddy rice. A challenge of modern agricultural practices is to reverse the impact cropping has had on greenhouse gas emissions and the global climate. There is an increasing demand for agriculture to provide food security as well as a range of other ecosystem services. Depending on ecosystem management, different practices may involve trade-offs and synergies, and these must be considered to work toward desirable management systems. Solution toward food security should not only focus on agricultural management practices, but also on strategies to reduce food waste, more socially-just distribution of resources, changes in lifestyle including decarbonization of the economy, as well as reducing human population growth.

    Cathryn A. O'SULLIVAN, Elliott G. DUNCAN, Margaret M. ROPER, Alan E. RICHARDSON, John A. KIRKEGAARD, Mark B. PEOPLES

    ● First evidence of BNI capacity in canola.

    ● BNI level was higher in canola cv. Hyola 404RR than in B. humidicola, the BNI positive control.

    ● BNI in canola may explain increased N immobilization and mineralization rates following a canola crop which may have implications for N management in rotational farming systems that include canola.

    A range of plant species produce root exudates that inhibit ammonia-oxidizing microorganisms. This biological nitrification inhibition (BNI) capacity can decrease N loss and increase N uptake from the rhizosphere. This study sought evidence for the existence and magnitude of BNI capacity in canola ( Brassica napus). Seedlings of three canola cultivars, Brachiaria humidicola (BNI positive) and wheat ( Triticum aestivum) were grown in a hydroponic system. Root exudates were collected and their inhibition of the ammonia oxidizing bacterium, Nitrosospira multiformis, was tested. Subsequent pot experiments were used to test the inhibition of native nitrifying communities in soil. Root exudates from canola significantly reduced nitrification rates of both N. multiformis cultures and native soil microbial communities. The level of nitrification inhibition across the three cultivars was similar to the well-studied high-BNI species B. humidicola. BNI capacity of canola may have implications for the N dynamics in farming systems and the N uptake efficiency of crops in rotational farming systems. By reducing nitrification rates canola crops may decrease N losses, increase plant N uptake and encourage microbial N immobilization and subsequently increase the pool of organic N that is available for mineralization during the following cereal crops.

    Jonathan STORKEY, Andrew J. MACDONALD

    ● Data from the Park Grass Experiment shows inherent trade-offs between species richness, biomass production and soil organic carbon.

    ● Soil organic carbon is positively correlated with biomass production that increases with fertilizer additions.

    ● Variance in outcomes can be understood in terms of the dominant ecological strategies of the plant communities indicated by functional traits.

    ● There was an indication that data on traits associated with the spatiotemporal pattern of resource capture could be used to design species mixtures with greater resource use complementarity, increasing species richness without sacrificing productivity.

    ● Variance in soil organic carbon was positively correlated with pH.

    Quantifying the relationships between plant functional traits and ecosystem services has been promoted as an approach to achieving multifunctional grassland systems that balance productivity with other regulating, supporting and cultural services. Establishing trade-offs and synergies between traits and services has largely relied on meta-analyses of studies from different systems and environments. This study demonstrated the value of focused studies of long-term experiments in grassland systems that measure traits and services in the same space and time to better understand the ecological constraints underlying these trade-offs and synergies. An analysis is presented that uses data from the Park Grass Experiment at Rothamsted Research on above-ground productivity, species richness and soil organic carbon stocks to quantify the relationships between these three outcomes and the power of variance in plant functional traits in explaining them. There was a trade-off between plots with high productivity, nitrogen inputs and soil organic carbon and plots with high species richness that was explained by a functional gradient of traits that are indicative of contrasting strategies of resource acquisition of resource conservation. Examples were identified of using functional traits to identify opportunities for mitigating these trade-offs and moving toward more multifunctional systems.

    John A. RAVEN

    ● Aboveground to belowground energy transfer.

    ● Importance of symplasmic nature of sieve tubes.

    ● Hydraulic, electrical and chemical energy transfer.

    ● Decreased soil organic C storage over 8000 years.

    Interactions between above and below ground parts of plants can be considered under the (overlapping) categories of energy, material and information. Solar energy powers photosynthesis and transpiration by above ground structures, and drives most water uptake through roots and supplies energy as organic matter to below ground parts, including diazotrophic symbionts and mycorrhizas. Material transfer occurs as water and dissolved soil-derived elements transport up the xylem, and a small fraction of water moving up the xylem with dissolved organic carbon and other solutes down the phloem. The cytosolic nature of sieve tubes accounts for at least some of the cycling of K, Mg and P down the phloem. NO3 assimilation of above ground parts requires organic N transport down phloem with, in some cases, organic anions related to shoot acid-base regulation. Long-distance information transfer is related development, biotic and abiotic damage, and above and below ground resource excess and limitation. Information transfer can involve hydraulic, electrical and chemical signaling, with their varying speeds of transmission and information content. Interaction of above and below ground plant parts is an important component of the ecosystem service of storing atmospheric CO2 as organic C in soil, a process that has decreased since the origin of agriculture.

    Timothy S. GEORGE, Cathy HAWES, Tracy A. VALENTINE, Alison J. KARLEY, Pietro P. M. IANNETTA, Robin W. BROOKER

    ● Diversification enhances nature-based contributions to cropping system functions.

    ● Soil management to improve production and ecosystem function has variable outcomes.

    ● Management of the production-system to use legacy nutrients will reduce inputs.

    ● Intercrops, companion crops and cover crops improve ecological sustainability.

    ● Sustainable interventions within value chains are essential to future-proof agriculture.

    To achieve the triple challenge of food security, reversing biodiversity declines plus mitigating and adapting to climate change, there is a drive to embed ecological principles into agricultural, value-chain practices and decision-making. By diversifying cropping systems at several scales there is potential to decrease reliance on inputs, provide resilience to abiotic and biotic stress, enhance plant, microbe and animal biodiversity, and mitigate against climate change. In this review we highlight the research performed in Scotland over the past 5 years into the impact of the use of ecological principles in agriculture on sustainability, resilience and provision of ecosystem functions. We demonstrate that diversification of the system can enhance ecosystem functions. Soil and plant management interventions, including nature-based solutions, can also enhance soil quality and utilization of legacy nutrients. Additionally, this is facilitated by greater reliance on soil biological processes and trophic interactions. We highlight the example of intercropping with legumes to deliver sustainability through ecological principles and use legumes as an exemplar of the innovation. We conclude that there are many effective interventions that can be made to deliver resilient, sustainable, and diverse agroecosystems for crop and food production, and these may be applicable in any agroecosystem.

    Ruqiang ZHANG, Zixi HAN, Qiaofang LU, Kang WANG, Yanjie CHEN, Wen-Feng CONG, Fusuo ZHANG

    ● Plant and soil biodiversity underline healthy dairy farms with less agrochemical inputs.

    ● Biodiversity-driven integrative approaches support healthy soils and high-quality milk products.

    ● Biodiversity-based modern farms can achieve high profitability with less environmental impacts.

    Producing sufficient high-quality forage to meet the increasing domestic demand for safe and nutritious milk products is one of the critical challenges that Chinese dairy farms are facing. The increased forage biomass production, mainly contributed by agrochemicals inputs in China, is accompanied by tremendous impacts on the ecology of dairy farms and soil quality. This paper presents a framework for healthy dairy farms in which targeted management practices are applied for quality milk products with minimal adverse environmental impacts. The paper also summarizes biodiversity management practices at the field and landscape scales toward lessening inputs of water, fertilizers, pesticides and mitigating soil compaction. Dairy farming with biodiversity-driven technologies and solutions will be more productive in producing quality milk and minimizing environmental damage.

    Emily C. COOLEDGE, David R. CHADWICK, Lydia M. J. SMITH, Jonathan R. LEAKE, Davey L. JONES

    ● Arable-ley rotations can alleviate soil degradation and erosion.

    ● Multispecies leys can improve livestock health and reduce greenhouse gas emissions.

    ● Ley botanical composition is crucial for determining benefits.

    ● Lack of livestock infrastructure in arable areas may prevent arable-ley uptake.

    ● Long-term (10–25 years) research is needed to facilitate evidence-based decisions.

    Agricultural intensification and the subsequent decline of mixed farming systems has led to an increase in continuous cropping with only a few fallow or break years, undermining global soil health. Arable-ley rotations incorporating temporary pastures (leys) lasting 1–4 years may alleviate soil degradation by building soil fertility and improving soil structure. However, the majority of previous research on arable-ley rotations has utilized either grass or grass-clover leys within ungrazed systems. Multispecies leys, containing a mix of grasses, legumes, and herbs, are rapidly gaining popularity due to their promotion in agri-environment schemes and potential to deliver greater ecosystem services than conventional grass or grass-clover leys. Livestock grazing in arable-ley rotations may increase the economic resilience of these systems, despite limited research of the effects of multispecies leys on ruminant health and greenhouse gas emissions. This review aims to evaluate previous research on multispecies leys, highlighting areas for future research and the potential benefits and disbenefits on soil quality and livestock productivity. The botanical composition of multispecies leys is crucial, as legumes, deep rooted perennial plants (e.g., Onobrychis viciifolia and Cichorium intybus) and herbs (e.g., Plantago lanceolata) can increase soil carbon, improve soil structure, reduce nitrogen fertilizer requirements, and promote the recovery of soil fauna (e.g., earthworms) in degraded arable soils while delivering additional environmental benefits (e.g., biological nitrification inhibition and enteric methane reduction). Multispecies leys have the potential to deliver biologically driven regenerative agriculture, but more long-term research is needed to underpin evidence-based policy and farmer guidance.

    Ting LUO, Prakash LAKSHMANAN, Zhongfeng ZHOU, Yuchi DENG, Yan DENG, Linsheng YANG, Dongliang HUANG, Xiupeng SONG, Xihui LIU, Wen-Feng CONG, Jianming WU, Xinping CHEN, Fusuo ZHANG

    ● Cost escalation and declining profits evident in sugarcane production in China.

    ● Monoculture and fertilizer overuse causes poor soil health, crop productivity plateau.

    ● Matching crop nutrient demand and supply key to recovery of sugarcane soils.

    ● Inorganic inputs need to be replaced with organic sources to restore soil health and sustainability.

    ● Integrated multidisciplinary solution for sustainable sugarcane cropping system needed.

    Demand for sugar is projected to grow in China for the foreseeable future. However, sugarcane production is unlikely to increase due to increasing production cost and decreasing profit margin. The persisting sugarcane yield plateau and the current cropping system with fertilizer overuse, soil acidification and pests and diseases remain the major productivity constraints. Sugarcane agriculture supports the livelihood of about 28 million farmers in South China; hence, sustaining it is a socioeconomic imperative. More compellingly, to meet the ever-increasing Chinese market demand, annual sugar production must be increased from the current 10 Mt to 16 Mt by 2030 of which 80% to 90% comes from sugarcane. Therefore, increasing sugar yield and crop productivity in an environmentally sustainable way must be a priority. This review examines the current Chinese sugarcane production system and discuss options for its transition to a green, sustainable cropping system, which is vital for the long-term viability of the industry. This analysis shows that reducing chemical inputs, preventing soil degradation, improving soil health, managing water deficit, provision of clean planting material, and consolidation of small farm holdings are critical requirements to transform the current farming practices into an economically and environmentally sustainable sugarcane cropping system.

    Léa KERVROËDAN, David HOUBEN, Julien GUIDET, Julia DENIER, Anne-Maïmiti DULAURENT, Elisa MARRACCINI, Amandine DELIGEY, Charlotte JOURNEL, Justine LAMERRE, Michel-Pierre FAUCON

    ● Agri-environmental assessment of food, feed and/or biogas cropping systems (CS).

    ● Four-year experiment for the agri-environmental assessment of two innovative CS.

    ● Biogas CS has equal soil returned biomass than food CS but higher exported biomass.

    ● Feed and biogas CS present higher biomass productivity, but higher CO2 emissions.

    ● CO2 emissions related to produced biomass are 26% (±5%) lower in biogas CS.

    Bioenergy, currently the largest renewable energy source in the EU (64% of the total renewable energy consumption), has sparked great interest to meet the 32% renewable resources for the 2030 bioeconomy goal. The design of innovative cropping systems informed by bioeconomy imperatives requires the evaluate of the effects of introducing crops for bioenergy into conventional crop rotations. This study aimed to assess the impacts of changes in conventional cropping systems in mixed dairy cattle farms redesigned to introduce bioenergy crops either by increasing the biomass production through an increase of cover crops, while keeping main feed/food crops, or by substituting food crops with an increase of the crop rotation length. The assessment is based on the comparison between conventional and innovative systems oriented to feed and biogas production, with and without tillage, to evaluate their agri-environmental performances (biomass production, nitrogen fertilization autonomy, greenhouse gas emissions and biogas production). The result showed higher values in the biogas cropping system than in the conventional and feed ones for all indicators, biomass productivity (27% and 20% higher, respectively), nitrogen fertilization autonomy (26% and 73% higher, respectively), methanogenic potential (77% and 41% higher, respectively) and greenhouse gas emissions (15% and 3% higher, respectively). There were no negative impacts of no-till compared to the tillage practice, for all tested variables. The biogas cropping system showed a better potential in terms of agri-environmental performance, although its greenhouse gas emissions were higher. Consequently, it would be appropriate to undertake a multicriteria assessment integrating agri-environmental, economic and social performances.

    Jeroen C. J. GROOT, Xiaolin YANG

    ● Impacts of 30 cropping systems practiced on the North China Plain were evaluated.

    ● Trade-offs were assessed among productive, economic and environmental indicators.

    ● An evolutionary algorithm was used for multi-objective optimization.

    ● Conflict exists between productivity and profitability versus lower ground water decline.

    ● Six strategies were identified to jointly mitigate the trade-offs between objectives.

    Since the Green Revolution cropping systems have been progressively homogenized and intensified with increasing rates of inputs such as fertilizers, pesticides and water. This has resulted in higher crop productivity but also a high environmental burden due to increased pollution and water depletion. To identify opportunities for increasing the productivity and reducing the environmental impact of cropping systems, it is crucial to assess the associated trade-offs. The paper presents a model-based analysis of how 30 different crop rotations practiced in the North China Plain could be combined at the regional level to overcome trade-offs between indicators of economic, food security, and environmental performance. The model uses evolutionary multi-objective optimization to maximize revenues, livestock products, dietary and vitamin C yield, and to minimize the decline of the groundwater table. The modeling revealed substantial trade-offs between objectives of maximizing productivity and profitability versus minimizing ground water decline, and between production of livestock products and vitamin C yield. Six strategies each defining a specific combination of cropping systems and contributing to different extents to the various objectives were identified. Implementation of these six strategies could be used to find opportunities to mitigate the trade-offs between objectives. It was concluded that a holistic analysis of the potential of a diversity cropping systems at a regional level is needed to find integrative solutions for challenges due to conflicting objectives for food production, economic viability and environmental protection.

    Jianxiang XU, Yunzhou LI, Yinkun YAO, Jie ZHAO, Jingyue TANG, Zixuan FENG