Agriculture practices developed since the middle of the last century have led to the degradation of different resources and made it necessary to promote agricultural models that are less aggressive towards nature. Sustainable agricultural growth requires a more efficient use of land. An experimental model was designed with four treatments in the Campo de Cartagena area (SE Spain): biosolarization with manure (BSM), biosolarization with brassicas (BB), solarization (S), and a pilot test (PT). The general objective was to determine by means of rapid response indicators the changes occurring in soil properties as a consequence of the implementation of these solarization or biosolarization practices and their influence on the quality and yield of a lettuce crop. The results show that there was no significant response in the physical and biological properties of the soil. Physicochemical properties such as pHw, and electrical conductivity (ECe), as well as chemicals such as total nitrogen (TN) and the content of some macro and micronutrients, can be considered as rapid response indicators. The highest yields (Yc) and highest commercial quality (Mc) of lettuce were obtained in the BB and BSM treatments (Yc > 23,000 kg ha−1; Mc > 413 g). These treatments resulted in biological NO3− sequestration and, in the case of BB, salt immobilization (ECe: 6 dS m−1). According to these results, BSM and BB can be recommended for sustainable agriculture and even as valid methods for the recovery of soils affected by salts and NO3−. Our results should increase the feasibility of these techniques in semiarid areas.

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Rapid Response Indicators for Predicting Changes in Soil Properties Due to Solarization or Biosolarization on an Intensive Horticultural Crop in Semiarid Regions

OUP accepted manuscript

Endophytes are critical for plant growth and health. Tea is an economically important crop in China. However, little is known about the distribution pattern and potential functions of endophytic communities in tea trees. In this study, two genotypes (BXZ and MF) cultivated under the same conditions were selected, and endophytic bacteria and fungi were analyzed through 16S rRNA and ITS high-throughput sequencing technologies, respectively. For endophytic bacteria, root tissues harbored the most diverse endophytes, followed by stems and old leaves, and new leaves possessed the lowest diversity. In contrast, old leave tissues harbored more diverse endophytic fungi than did root and stem tissues. Most of the dominant endophytes showed obvious cultivar and tissue preferences. Tissue type played a more important role in shaping community structure than did cultivar. Nevertheless, some endophytic bacterial groups, which mainly affiliated to Chryseobacterium, Sphingomonas, Rhizobium, Morganella, Methylobacterium and Comamonadaceae, could parasitize different tissues, and the average relative abundance of endophytic bacteria was as high as 72.57%. Some endophytic fungal populations, such as Colletotrichum, Uwebraunia, Cladosporium, and Devriesia, could also parasitize tea, and the relative abundance accounted for approximately 25.70–97.26%. The cooperative relationship between endophytic bacteria and fungi in the new leaves was stronger than that in the old leaves, which can better participate in the metabolism of tea material.

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Distribution pattern of endophytic bacteria and fungi in tea plants

Abstract Biofumigation has been proposed as an alternative to soil fumigation to manage soil-borne diseases including potato early dying disease complex (PED). This study examined the potential of using brown mustard ( Mustard juncea ) biofumigation to manage PED under rain-fed potato production in New Brunswick, Canada in two trials between 2017 and 2020 in comparison with chloropicrin fumigation and a conventional barley rotation. Biofumigation increased yield in one trial, but not in a second trial where the potato crop experienced severe drought, whereas chloropicrin fumigation increased yield in both trials. Biofumigation was effective in suppressing root-lesion nematode (RLN, Pratylenchus spp.) counts in both trials, but was ineffective in suppressing V. dahliae population density. Chloropicrin fumigation was effective in suppressing RLN counts and V. dahliae population density only in the hill where injected, but the effect was short-lived as the population density of V. dahliae in the hill increased to the level of the control in one potato growing season. Biofumigation may be an alternative to chloropicrin fumigation in managing PED, particularly in fields with high RLN population but relatively low Verticillium population density. However, neither biofumigation nor fumigation used alone may be sustainable in the short-term potato rotations commonly used in New Brunswick, and additional beneficial practices are required to sustain productivity in the long-term. 

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Effect of Biofumigation on Population Densities of Pratylenchus spp. and Verticillium spp. and Potato Yield in Eastern Canada

Organic farming is a holistic production management system that promotes and enhances agroecosystem health, including biodiversity, biological cycles and soil biological activity, and consequently, it is an efficient and promising approach for sustainable agriculture within a circular and green economy. There has been a rise in the consumption of organic vegetables in the last years because of their organoleptic properties, higher nutritive value and lower risk of chemical residues harmful to health. The recent scientific evidence regarding the use of the major elements responsible for organic vegetable crop production indicates plant material, soil management and crop nutrition, soil disinfection, crop management and pest, disease and weed management. These techniques are the focus of this study. In general, the main outcomes of this review demonstrate that a great effort of innovation and research has been carried out by industry, researchers and farmers in order to reduce the environmental impact of the established and innovative horticultural practices while satisfying the requirements of consumers. However, research-specific studies should be carried out in different farming systems and pedoclimatic conditions to achieve the highest efficiency of these horticultural practices.

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Current Trends in Organic Vegetable Crop Production: Practices and Techniques

Chemical fumigation and biofumigation are used to reduce soil-borne diseases in agricultural production systems; however, other essential soil processes such as the soil nitrogen (N) cycle may also be affected. This study compared the effects of chemical fumigation and biofumigation on soil net N mineralization, nitrification, denitrification, and soil nitrifier and denitrifier abundance. Six treatments were compared using soil microcosms over a 160-day incubation period: fumigation with chloropicrin; fumigation with metam sodium used alone (MS) or combined with barley plant residues (MSBR); biofumigation with mustard residues; addition of non-biofumigant barley residues; and an untreated control. Biofumigation did not inhibit soil nitrification, whereas chemical fumigation with MS (with or without barley) and chloropicrin inhibited nitrification for 16 and 64 days, respectively. Biofumigation, barley residues, and MSBR increased soil respiration, N2O emission, and denitrification rates. However, biofumigation had lower denitrification and N2O cumulative emissions and rates compared to barley residues, suggesting that biofumigation may reduce N2O production pathways. All chemical fumigation treatments significantly decreased nitrifier gene abundance compared to biofumigation; however, only chloropicrin decreased the abundance of denitrifying genes. After 160 days, 22% of the added plant residue dry matter remained in the MSBR-treated soil, which was ∼2-fold greater than the barley-treated soil, indicating chemical fumigation may also affect the carbon cycle. Overall, these results suggest that chemical fumigation, especially with chloropicrin, has a greater impact on nitrification and nitrifier and denitrifier gene abundance than biofumigation with mustard residues.

Louise Sennett

Papers

Influence of chemical fumigation and biofumigation on soil nitrogen cycling processes and nitrifier and denitrifier abundance

Diverse compost products influence soil bacterial and fungal community diversity in a potato crop production system