Organic amendments modulate the crop yield and rhizospheric bacterial community diversity: a 3-year field study with Cajanus cajan

Excessive use of chemicals to enhance soil nutrient status and crop yield has resulted in a decline in soil health. Organic farming promotes organic amendments, which help to balance the ecosystem. Understanding the dynamic patterns of belowground microbial populations is essential for developing sustainable agricultural systems. Therefore, the study was designed to evaluate the effect of different agri-practices on rhizospheric bacterial diversity and crop yield in an Indian agricultural system. A 3-year field experiment was set up in a randomized block design using Cajanus cajan as a model crop, comparing conventional farming with organic practice (with animal manure and bio-compost as amendments). Plant and rhizospheric soil samples were collected at the harvest stage for assessing various growth attributes, and for characterizing rhizospheric bacterial diversity. Enhanced crop productivity was seen in conventional farming, with a 2.2-fold increase in grain yield over control. However, over the 3 years, an overall positive impact was observed in the bio-compost-based organic amendment, in terms of bacterial abundance, over other treatments. At the harvest stage of the third cropping season, the bacterial diversity in the organic treatments showed little similarity to the initial bacterial community composition of the amendment applied, indicating stabilization along the growth cycles. The study emphasizes the significance of the choice of the amendment for ushering in agricultural sustainability.

Natural farming improves crop yield in SE India when compared to conventional or organic systems by enhancing soil quality

Zero Budget Natural Farming (ZBNF) is a grassroot agrarian movement and a state backed extension in Andhra Pradesh, and has been claimed to potentially meet the twin goals of global food security and environmental conservation. However, there is a lack of statistically evaluated data to support assertions of yield benefits of ZBNF compared to organic or conventional alternatives, or to mechanistically account for them. In order to fill this gap, controlled field experiments were established in twenty-eight farms across six districts, spanning over 800 km, over three cropping seasons. In these experiments, we compared ZBNF (no synthetic pesticides or fertilisers, home-made inputs comprising desi cow dung and urine with mulch) to conventional (synthetic fertilisers and pesticides) and organic (no synthetic pesticides or fertilisers, no mulch, purchased organic inputs, e.g. farmyard manure and vermicompost) treatments, all with no tillage. Comparisons were made in terms of yield, soil pH, temperature, moisture content, nutrient content and earthworm abundance. Our data shows that yield was significantly higher in the ZBNF treatment (z score = 0.58 ± 0.08), than the organic (z= -0.34 ± 0.06) or conventional (-0.24 ± 0.07) treatment when all farm experiments were analysed together. However, the efficacy of the ZBNF treatment was context specific and varied according to district and the crop in question. The ZBNF yield benefit is likely attributed to mulching, generating a cooler soil, with a higher moisture content and a larger earthworm population. There were no significant differences between ZBNF and the conventional treatment in the majority of nutrients. This is a particularly important observation, as intensive use of synthetic pesticides and fertilisers comes with a number of associated risks to farmers' finances, human health, greenhouse gas emissions, biodiversity loss and environmental pollution. However, long-term field and landscape scale trials are needed to corroborate these initial observations.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13593-023-00884-x.

Smart nanomaterial and nanocomposite with advanced agrochemical activities

Conventional agriculture solely depends upon highly chemical compounds that have negatively ill-affected the health of every living being and the entire ecosystem. Thus, the smart delivery of desired components in a sustainable manner to crop plants is the primary need to maintain soil health in the upcoming years. The premature loss of growth-promoting ingredients and their extended degradation in the soil increases the demand for reliable novel techniques. In this regard, nanotechnology has offered to revolutionize the agrotechnological area that has the imminent potential over conventional agriculture and helps to reform resilient cropping systems withholding prominent food security for the ever-growing world population. Further, in-depth investigation on plant-nanoparticles interactions creates new avenues toward crop improvement via enhanced crop yield, disease resistance, and efficient nutrient utilization. The incorporation of nanomaterial with smart agrochemical activities and establishing a new framework relevant to enhance efficacy ultimately help to address the social acceptance, potential hazards, and management issues in the future. Here, we highlight the role of nanomaterial or nanocomposite as a sustainable as well stable alternative in crop protection and production. Additionally, the information on the controlled released system, role in interaction with soil and microbiome, the promising role of nanocomposite as nanopesticide, nanoherbicide, nanofertilizer, and their limitations in agrochemical activities are discussed in the present review.

Effect of different rice farming practices on the bioavailability of mercury: A mesocosm experiment with common goldfish (Carassius auratus)

Wetlands such as rice paddies are important ecosystems that provide habitat for a numerous range of species but are considered as a major source of mercury in the most toxic form of methylmercury. An in situ mesocosm experiment was conducted during the rice cultivation season of 2018 in rice paddies from the Ebro Delta (NE Spain) to investigate the bioaccumulation of mercury in fish. Common goldfish (Carassius auratus) were exposed to three types of rice-fields subject to different agricultural management (conventional or ecological agriculture) and different hydric practices (wet, dry) and were sampled monthly. Total mercury concentration in fish increased over time for almost all the fields under study, but the mercury increase was particularly higher for fish exposed to ecological fields. We conducted δ¹⁵N and δ¹³C measurements to follow up fish diet changes within or among fields. The results have shown there were no variations in the diet of the fish over time within fields, although differences among management practices were observed, which could explain to some extent the THg variation in fish exposed to each of the agricultural practices. Results indicate that wetting and drying rice fields might be a greater source of mercury for fish and a potential hotspot for MeHg production enhanced by physicochemical parameters. Thus, mercury bioaccumulation in fish inhabiting rice paddies depend on several factors what, in turn, could lead to biomagnification across the food webs.

Assessment of soil health parameters and application of the sustainability index to fields under conservation agriculture for 3, 6, and 9 years in India

The effect of duration of conservation agriculture adoption on soil carbon dynamics and system sustainability was evaluated on farms of 30 villages in the Nilokheri block of Karnal district, Haryana, India. Sustainability was evaluated, in which a number of soil physical, chemical, and biological parameters were measured and a Sustainability Index (SI) was applied. Soil samples were collected from existing conservation agriculture (CA) and conventional tillage (CT) farms. Villages under CA practices were subdivided as CA3, CA6, and CA9 based on the number of years of CA practice adoption. Results showed that bulk density (BD) of 0-15 cm soil depth was 7% greater in CA3 plots, whereas in CA6 and CA9 plots BD values were only 2% and 3% higher than CT. Soil organic carbon (SOC) in 0-15 cm soil depth was found to be greater by 16.32% in CA3 than CT plots, whereas SOC was higher by 38.77% and 61.22% in CA6 and CA9. In CA, for the 0-15 and 15-30 cm soil depths, labile pools were 36% and 22% greater than CT, respectively. For both the soil depths in CA, the recalcitrant pool was 12% and 9% more than CT, respectively. Microbial biomass carbon (MBC) values of the 0-15 cm soil depth were increased over CT by 18.57%, 47.08%, and 71.5% for CA3, CA6, and CA9 respectively. In CA plots, the SI of 0-15 cm soil depth ranged between cumulative ratings (CR) of 18-21, which indicates that CA practice is "sustainable" for both soil depths. For CT, CR ranged from 25 to 30 for both soil depths resulting in a SI of "sustainability with high input". Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) scores showed that SOC had the maximum weight (0.96) towards sustainability, giving it a rank of 1. Effective rooting depth (ERD), BD, texture, and wilting point (WP) ranked 2, 3, 4 and 5, respectively, indicating their corresponding weight of contribution towards the SI. Farmers in the Karnal district should be encouraged to adopt CA practices as they can increase SOC and move the systems from "sustainable with high input" to "sustainable".

Belowground fungal community diversity, composition and ecological functionality associated with winter wheat in conventional and organic agricultural systems

Understanding the impacts of agricultural practices on belowground fungal communities is crucial in order to preserve biological diversity in agricultural soils and enhance their role in agroecosystem functioning. Although fungal communities are widely distributed, relatively few studies have correlated agricultural production practices. We investigated the diversity, composition and ecological functionality of fungal communities in roots of winter wheat (Triticum aestivum) growing in conventional and organic farming systems. Direct and nested polymerase chain reaction (PCR) amplifications spanning the internal transcribed spacer (ITS) region of the rDNA from pooled fine root samples were performed with two different sets of fungal specific primers. Fungal identification was carried out through similarity searches against validated reference sequences (RefSeq). The R package ‘picante’ and FUNGuild were used to analyse fungal community composition and trophic mode, respectively. Either by direct or cloning sequencing, 130 complete ITS sequences were clustered into 39 operational taxonomic units (OTUs) (25 singletons), belonging to the Ascomycota (24), the Basidiomycota (14) and to the Glomeromycota (1). Fungal communities from conventional farming sites are phylogenetically more related than expected by chance. Constrained ordination analysis identified total N, total S and Pcal that had a significant effect on the OTU’s abundance and distribution, and a further correlation with the diversity of the co-occurring vegetation could be hypothesised. The functional predictions based on FUNGuild suggested that conventional farming increased the presence of plant pathogenic fungi compared with organic farming. Based on diversity, OTU distribution, nutrition mode and the significant phylogenetic clustering of fungal communities, this study shows that fungal communities differ across sampling sites, depending on agricultural practices. Although it is not fully clear which factors determine the fungal communities, our findings suggest that organic farming systems have a positive effect on fungal communities in winter wheat crops.

Aquaponics: a sustainable alternative to conventional agriculture in Egypt - a pilot scale investigation

Conventional agriculture has been widely used to overcome food scarcity in Egypt, but in turn created new environmental, social, and economic problems. Aquaponics has a huge potential as a sustainable solution since it demonstrates promising results for urban food development while providing new entrepreneurship and start-up opportunities. Although it presents a big opportunity especially for developing countries like Egypt, it still requires further studies and researches to fully overcome foreseen challenges. This study discusses the possibility of implementing aquaponics as an alternative to conventional agriculture in Egypt through a comparison between aquaponics and conventional agriculture. The first section of this investigation analyzes the economic feasibility of aquaponics in terms of capital and operational expenditure costs. Then, an experimental comparative study is carried out examining two pilot-scale aquaponics systems (Deep water Culture system and Integrated Aqua-Vegaculture system), where crop quality (vitamins, heavy metals, and pesticides residues) of the two systems has been compared among each other, as well as to that of the commercially available organic food available in supermarkets. Results indicated that both systems produce high-quality safe organic food. The economic feasibility analysis indicated that Integrated Aqua-Vegaculture System is producing more crops with a wider variety of almost 20% less capital expenditure and operational expenditure costs. Fish production for both systems was close, yet slightly higher in Deep Water Culture. Although, on the short term, aquaponics entails relatively high capital and operational expenditure costs compared with conventional agriculture; yet, on the long term, it is more profitable, while saving up to 85% of the water wasted by conventional farming techniques. Finally, the study discusses the main limitations, drawbacks, and future of aquaponics in Egypt where public awareness and a new mindset are needed to highlight the link between agriculture and sustainability.

Metabolomics for organic food authentication: Results from a long-term field study in carrots

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The agricultural origin of carrots could be predicted.

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Using yearly harvested samples allowed 100% correct classification of unknowns.

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Metabolomic fingerprinting showed potential for organic food authentication.

Increasing demand for organic products and their premium prices make them an attractive target for fraudulent malpractices. In this study, a large-scale comparative metabolomics approach was applied to investigate the effect of the agronomic production system on the metabolite composition of carrots and to build statistical models for prediction purposes. Orthogonal projections to latent structures-discriminant analysis (OPLS-DA) was applied successfully to predict the origin of the agricultural system of the harvested carrots on the basis of features determined by liquid chromatography–mass spectrometry. When the training set used to build the OPLS-DA models contained samples representative of each harvest year, the models were able to classify unknown samples correctly (100% correct classification). If a harvest year was left out of the training sets and used for predictions, the correct classification rates achieved ranged from 76% to 100%. The results therefore highlight the potential of metabolomic fingerprinting for organic food authentication purposes.