Vegetable Cropping Systems Research Articles

Effect of straw biochar application on soil carbon, greenhouse gas emissions and nitrogen leaching: A vegetable crop rotation field experiment

AbstractIntensive vegetable crop systems are rapidly developing, with consequences for greenhouse gas (GHGs) emissions, nitrogen leaching and soil carbon. We undertook a field trial to explore the effect of biochar application (0, 10, 20 and 40 t ha−1) on these factors in lettuce, water spinach and ice plant rotation. Our results show that the 20 and 40 t ha−1 soil treatments resulted in the SOC content being 26.3% and 29.8% higher than the control (0 t ha−1), respectively, with significant differences among all treatments (p < .05). Biochar application caused N2O emissions to decrease during the lettuce and water spinach seasons, by 1.5%–33.6% and 12.4%–40.5%, respectively, compared the control, with the 20 t ha−1 application rate resulting in the lowest N2O emissions. Biochar also decreased the dissolved nitrogen (DN) concentration in leachate by 9.8%–36.2%, following a 7.3%–19.9% reduction in dissolved nitrogen in the soil. Similarly, biochar decreased the nitrate (NO3−) concentrations in leachate by 3.9%–30.2%, following a 3.8%–16.7% reduction in the soil nitrate level. Overall, straw biochar applied at rate of 20 t ha−1 produced the lowest N2O emissions and N leaching, while, increasing soil carbon.

Localized phosphorus promotes nutrient productivity of Brassica chinensis genotype with strong root morphological plasticity

Crops adjust root morphological and/or exudation traits in response to phosphorus (P) availability and localized P, governing crop productivity. However, how the intraspecific plasticity of root P-acquisition strategies influences plant adaptation to localized P fertilization across doses remains obscure. Root P-acquisition traits were assessed in Brassica chinensis L. Xiaqing and Yanchun grown in soil with four mineral P fertilization levels (0, 15, 24, and 30 kg P ha−1) and with broadcasted and localized P across two levels (15 and 24 kg P ha−1) to characterize efficient strategies in relation to large plant P productivity. The Xiaqing genotype stimulated the growth of roots with large specific lengths and increased the exudation of acid phosphatase and carboxylates under 15 kg P ha−1 fertilization compared to those in 24 and 30 kg P ha−1 soil. Conversely, Yanchun only increased root elongation in 15 kg P ha−1 soil compared with crops in soil fertilized with 30 kg P ha−1. Xiaqing and Yanchun stimulated local root growth in P-rich soil with 15 and 24 kg P ha−1, but with longer roots in the former than the latter genotype. Localized P at the 15 kg P ha−1 level, compared with 24 kg P ha−1, increased root length density in the patchy soil zone and promoted P acquisition in Xiaqing and Yanchun. In conclusion, the Xiaqing genotype exhibited strong root plasticity in response to low and localized P application compared with the Yanchun genotype. Nutrient-efficient genotype coupling with localized fertilization is important to increase crop yield and save fertilizer in vegetable cropping systems.

Can multi-cropping affect soil microbial stoichiometry and functional diversity, decreasing potential soil-borne pathogens? A study on European organic vegetable cropping systems.

Crop diversification in spatial and temporal patterns can optimize the synchronization of nutrients plant demand and availability in soils, as plant diversity and soil microbial communities are the main drivers of biogeochemical C and nutrient cycling. The introduction of multi-cropping in organic vegetable production can represent a key strategy to ensure efficient complementation mediated by soil microbiota, including beneficial mycorrhizal fungi. This study shows the effect of the introduction of multi-cropping in five European organic vegetable systems (South-West: Italy; North-West: Denmark and Belgium; North-East: Finland and Latvia) on: (i) soil physicochemical parameters; (ii) soil microbial biomass stoichiometry; (iii) crop root mycorrhization; (iv) bacterial and fungal diversity and composition in crop rhizosphere; (v) relative abundance of selected fungal pathogens species. In each site, three cropping systems were considered: (1) crop 1—monocropping; (2) crop 2—monocropping; (3) crop 1—crop 2—intercropping or strip cropping. Results showed that, just before harvest, multi-cropping can increase soil microbial biomass amount and shape microbial community toward a predominance of some bacteria or fungi phyla, in the function of soil nutrient availability. We mainly observed a selection effect of crop type on rhizosphere microbiota. Particularly, Bacteroidetes and Mortierellomycota relative abundances in rhizosphere soil resulted in suitable ecological indicators of the positive effect of plant diversity in field, the first ones attesting an improved C and P cycles in soil and the second ones a reduced soil pathogens' pressure. Plant diversity also increased the root mycorrhizal colonization between the intercropped crops that, when properly selected, can also reduce the relative abundance of potential soil-borne pathogens, with a positive effect on crop productivity in long term.

Biochar-Induced Mitigation Potential of Greenhouse Gas Emissions Was Enhanced under High Soil Nitrogen Availability in Intensively-Irrigated Vegetable Cropping Systems

Intensive irrigation coupled with excessive nitrogen (N) fertilizer input has resulted in high soil greenhouse gas (GHG) emissions in vegetable cropping systems. Biochar as a soil amendment has been advocated as a desirable option to reduce GHG emissions in agricultural systems, but its interactive effects with soil N availability in vegetable systems have yet to be clarified. We performed a field study to examine how biochar interacts with N fertilizer in driving annual methane (CH4) and nitrous oxide (N2O) emissions from an intensively-irrigated greenhouse vegetable cropping system acting as both sources of atmospheric CH4 and N2O in subtropical China. Biochar amendment significantly increased soil CH4 emissions by 33% and 85%, while it decreased soil N2O emissions by 22% and 12% with and without N fertilizer input, respectively. Fertilizer N combination weakened the positive response of CH4 to biochar while it enhanced the mitigation potential of biochar for N2O. Annual direct emission factors of fertilizer N for N2O were estimated to be 1.35% and 1.94% for the fields with and without biochar amendment, respectively. Annual flux-sustained global warming potential (SGWP) and greenhouse gas intensity (GHGI) were significantly decreased by biochar amendment, and this mitigation effect was enhanced with fertilizer N combination. Altogether, we highlight that biochar can reconcile higher yield and lower climatic impact in intensive vegetable cropping systems in subtropical China, particularly in vegetable soils with high N availability.

Carbon-Phosphorus Coupling Governs Microbial Effects on Nutrient Acquisition Strategies by Four Crops.

Plants adjust root morphological and/or exudation traits in response to phosphorus (P) mobilization mediated by microorganisms. We hypothesized that straw application coupled with P fertilization would influence microbial P and then root nutrient-acquisition strategies related to crop growth. Root morphological (length and average diameter) and exudation traits (acid phosphatase and carboxylates) of Brassica chinensis, Solanum lycopersicum, Lactuca sativa, and Vigna unguiculata in response to microbial P dynamics were characterized in no-P and P-fertilized soil with/without straw addition. Straw addition increased the growth of fungi and bacteria, stimulating microbial P immobilization at day 24. The high microbial abundance was associated with four tested crops having short roots in straw-amended compared with no-straw soil at day 24. In straw-amended soil, B. chinensis and S. lycopersicum shifted toward root P-acquisition strategies based on fast elongation and strong carboxylate exudation from days 24 to 40. Such effective root P-acquisition strategies together with microbial P release increased shoot P content in S. lycopersicum in straw-amended compared with those without straw at day 40. Conversely, L. sativa and V. unguiculata produced short roots in response to the stable (or even increased) microbial P after straw addition till day 40. In straw-amended soil, high P application stimulated root elongation and carboxylate exudation in L. sativa and V. unguiculata, whereas carboxylate exudation by S. lycopersicum was decreased compared with the straw-amended but non-fertilized treatment at day 40. In summary, root P-acquisition strategies in response to microbial P differed among the tested crop species. Phosphorus fertilization needs to be highlighted when returning straw to enhance P-use efficiency in vegetable cropping systems.

Impact of Natural Farming Cropping System on Rural Households—Evidence From Solan District of Himachal Pradesh, India

Natural farming, popularly known as zero budget natural farming, is an innovative farming approach. It is low input based, climate resilient, and low cost farming system because all the inputs (insect repellents, fungicides, and pesticides) are made up of natural herbs and locally available inputs, thereby reducing the use of artificial fertilizers and industrial pesticides. It is becoming increasingly popular among the smallholder farmers of Himachal Pradesh. Under the natural farming system, 3 to 12 crops are cultivated together on the same area, along with leguminous crops as intercrop in order to ensure that no piece of land is wasted and utilized properly. This article focuses mainly on the different cropping systems of natural farming and comparing the economics of natural farming (NF) with conventional farming (CF) systems. Study shows that farmers adopted five major crop combinations under natural farming system, i.e., vegetables-based cropping system (e.g., tomato + beans + cucumber and cauliflower + pea + radish), vegetables-cereals-based cropping system, and other three more cropping systems discussed in this article. The results indicated that a vegetable-based cropping system has 19.68% more net return in Kharif season and 24.64% more net return in Rabi season as compared to conventional farming vegetable-based monocropping system. NF maximizes land use and reduces the chance of crop yield loss. NF has resulted in increased returns especially in the vegetable cropping system where reduction in cost was 30.73 per cent (kharif) and 11.88 per cent (rabi) across all crop combinations in comparison to CF. It is found in study that NF was cost savings from not using chemical fertilizers and pesticides, as well as higher benefit from intercrops.

Accumulation of essential mineral and toxic trace elements in crops and soils of vegetable cropping systems in central highlands of Sri Lanka

AbstractVegetables are widely cultivated in high rainfall and mountainous regions in Sri Lanka with poor soil conservation practices. Accumulation of essential mineral and toxic trace elements in the soils and widely cultivated vegetables of this region are poorly understood. One hundred soil and vegetable (i.e. cabbage, carrot and potato) samples were collected at the time of harvest and analysed for element concentrations. Soils contained high concentrations of essential mineral (N, P, K, Cu, Zn and Mn) and toxic trace elements (As, Cd and Pb). When comparing edible parts, cabbage contained the highest concentrations of mineral and toxic trace elements, and potato contained the lowest. Irrespective of the crop, edible parts contained high concentrations of N, P, K (14–35, 2–6, 15–24 g/kg, respectively), and Cu, Zn, Mn (2.5–6.7, 11–30, 8–147 mg/kg, respectively). Vegetables also contained As, Cd and Pb (0.04–1, 0.02–0.15, 0.02–0.26 mg/kg, respectively), but did not exceed the maximum permissible limits. Irrespective of the crop, 36–64 kg N, 6–11 kg P and 35–45 kg K per ha were removed with the harvest. According to the current rate of vegetable consumption by Sri Lankans (i.e. 240 g fresh weight (FW) per day), per capita consumption of 0.05–0.2 mg Cu, 0.45–0.65 mg Zn and 0.5–2 mg Mn per day through these vegetables was observed, i.e. 5–23% Cu, 7.5–11% Zn and 22–87% Mn of the recommended daily intake. Vegetables grown in the region served as a key source of essential mineral elements. However, agronomic mitigation strategies are needed to improve soil health and sustainability of these cropping systems.

Annual NO and N

Context Overuse of N fertiliser in vegetable cropping systems is known to release of nitric and nitrous oxide to the atmosphere in China. Optimisation of N fertilisation regimes has the potential to mitigate NO and N2O emissions from these N-rich systems. Aims We investigated the effects of different N fertilisation regimes on NO and N2O emissions, and vegetable yields, with particular efforts to estimate annual direct emission factors of NO and N2O under different N fertilisation regimes in greenhouse vegetable fields. Methods Annual NO and N2O fluxes were taken simultaneously using the static chamber-based method from a greenhouse vegetable system in south-east China with four N fertiliser treatments: (1) no N fertiliser (control); (2) chemical N fertiliser application (CF); (3) organic N fertiliser application (OF); and (4) organic-chemical mixed N fertiliser application (MF). Key results N fertilisers significantly increased NO and N2O emissions. Direct emission factors of N fertiliser for NO and N2O were the largest for MF, with an average of 0.99% and 0.67%, respectively. Vegetable yields were only significantly enhanced under OF treatment. Conclusions Relative to the use of chemical N fertiliser, the application of organic-chemical mixed N fertiliser showed not to be effective for mitigating NO and N2O emissions. Instead, sole application of organic N fertiliser was a viable option to enhance vegetable yields but without increasing NO and N2O emissions in greenhouse vegetable systems. Implications Substituting the use of chemical N fertiliser with organic N fertiliser input could benefitvegetable production but without stimulating NO and N2O emissions from vegetable cropping systems in sub-tropical China.

Preliminary N2O Emissions of Major Vegetable Cropping Systems in Peri-urban Hanoi, Vietnam

Crop management practices in intensive vegetable production can influence nitrous oxide (N2O) emissions from soils. This study quantified seasonal N2O emissions and N2O emission intensities, and investigated the factors driving emissions in different vegetable management practices. Emissions from four typical vegetable crops (two choy sums, a mustard, and a cabbage) were intensively measured over the 2016 autumn season on farms in Van Noi and Dang Xa communes in the Hanoi peri-urban area. Different N2O emissions were observed in the four leafy vegetable crops. The average daily emissions varied from 12.15 g to 40.08 g N2O-N ha-1 and the autumn season N2O emissions varied from 1.13 kg to 8.45 kg N2O-N ha-1 across the four crops. The greatest daily and season emissions were from cabbage, and the lowest were from mustard. Emission intensities varied among the types of vegetables and was the lowest at the mustard farm (37 kg CO2-e t-1), indicating that the crop management practices increased the mustard yield but retained a low N2O emission rate. Practices responsible for high N2O emissions were overuse of nitrogen fertilisers and furrow irrigation. An improvement in the farmers’ adoption of best practices in fertiliser application and irrigation could reduce N2O emissions without affecting crop productivity.

​Performance of Different Farming Practices in Legume based Cropping System under Mid-hills of H.P. Himalayas

Background: Increasing demands of food, depleting land, degrading land resources and changing climate are some of the important factors driving the cropping systems of any agro-ecological zone in the world. Cropping systems have been traditionally structured to maximize crop yields. Now, there is a strong need to design cropping systems which take into consideration the emerging social, economical and ecological or environmental concerns. Legumes can provide opportunities for increased productivity to be sustained because of their adaptability to various cropping patterns and ability to fix nitrogen. Legume-based crop rotation helps to conserve organic matter, maximise soil nitrogen, balance soil nutrients, maintain soil physical properties and break soil-borne disease cycles. Moreover, with increasing fertilizer prices and emphasis of the government for doubling the farmer’s income by reducing cost of cultivation, the current trend is to explore the possibility of supplementing chemical fertilizer with the organic ones, more particularly organic manures and bio-fertilizer of microbial origin. The current study is aimed to increase small and marginal farmer’s income and to reduce cost of cultivation through legume based vegetable cropping systems and to find out best farming practices. Methods: Field experiments were conducted at Organic Farm Holta, Department of Organic Agriculture and Natural farming, CSK HPKV, Palampur (H.P.) during kharif and rabi seasons of 2018-19 and 2019-20 on silty clay loam soil to study the performance of different farming practices in legume based cropping system under mid- hills of H.P. Himalayas. The experiment was laid out under Split plot design with three replications comprising of three sequences in legume vegetable-based cropping systems i.e., “Soybean-Onion”, “Okra-Pea” and “Mash-Garlic” under different farming practices i.e., Organic farming, Natural farming, Inorganic and Integrated farming practices. For comparison of different crops soybean equivalent yield and pea equivalent yields were calculated in kharif and rabi seasons, respectively. Result: In kharif seasons okra crop attained highest soybean equivalent yield followed by soybean and mash crop. In rabi seasons garlic crop attained highest pea grain equivalent yield followed by onion and pea crop. During both kharif seasons organic farming practices attained highest yield and was at par with integrated farming practices. Significantly highest yield was attained from integrated farming practices and was at par with organic farming practices in both rabi seasons. Highest net returns, net returns per rupee attained was in inorganic farming system. Highest cost of cultivation was found in organic farming practices.

Influence of the Environment and Vegetable Cropping Systems on Plant-Parasitic Nematode Communities in Southern Georgia

Plant-parasitic nematodes (PPN) limit yields of vegetable production in the United States. During the spring and fall cropping seasons of 2018, 436 fields in bare ground and plastic bed cropping systems were randomly sampled from 29 counties in southern Georgia. The incidence (%), mean relative abundance, and maximum relative abundance (nematodes per 100 cm3 of soil) of the 10 different PPN genera detected in 32 vegetable crops in bare ground and plastic bed cropping systems include Meloidogyne spp. (67.3%; mean, 292; maximum, 14,144), Nanidorus spp. (49.4%; mean, 6; maximum, 136), Mesocriconema spp. (39.6%; mean, 17; maximum, 340), Helicotylenchus spp. (31.6%; mean, 20; maximum, 1152), Pratylenchus spp. (20.1%; mean, 2; maximum, 398), Rotylenchulus spp. (5.9%; mean, 1; maximum, 116), Hoplolaimus spp. (12.6%; mean, 1; maximum, 78), Heterodera spp. (2.3%; mean, <1; maximum, 60), Tylenchorhynchus spp. (0.9%; mean, <1; maximum, 12), and Xiphinema spp. (0.2%; mean, <1; maximum, 2). A nonmetric multidimensional scaling analysis indicated that most environmental and geological factors (i.e., longitude, precipitation, soil moisture, sand and silt content, and soil electrical conductivity) had no apparent relationship with nematode counts, except for latitude, soil pH, and temperature. The multirank permutation procedure followed by indicator species analysis and nonparametric Kruskal-Wallis analysis of variance indicated that Meloidogyne spp. are the predominant PPN associated with plastic beds in the south region sampled. The south region consisted mainly of commercial fields that rotated multiple vegetables crops through the same plastic beds. All other PPNs were associated with bare ground beds in the north region that are commonly rotated with row crops. This study validates that Meloidogyne spp. are the most important PPN in vegetable fields of southern Georgia and suggests that cropping systems have a greater effect on PPN population dynamics than the environment.

Weed Suppression, Nitrogen Availability, and Cabbage Production Following Sunn Hemp or Sorghum-sudangrass

Cover crops included in a crop rotation can help increase nitrogen (N) availability to subsequent crops, raise soil organic matter, and suppress emergence and growth of various weed species. However, weed suppression by cover crops has mostly been investigated shortly after cover crop termination and not over a longer period spanning into the next cropping season. The effects of sunn hemp (Crotalaria juncea) and sorghum-sudangrass (Sorghum ×drummondi) planted the previous year on N availability before transplanting of late summer cabbage (Brassica oleracea), weed germination and growth, and cabbage yield was examined in field studies conducted in 2018 and 2019 at Pittstown, NJ. Results established that there was little evidence for a functional difference in soil N availability for fall cabbage production because of previous cover crop type. Heavy rainfall events both years may have caused major losses of available N that might otherwise be expected to come from N mineralization of residues of legume cover crop like sunn hemp. During the cover crop season, smooth pigweed (Amaranthus hybridus) and common lambsquarters (Chenopodium album) dry biomass was 77% and 82% lower, respectively, in sorghum-sudangrass compared with sunn hemp plots. The subsequent season following sorghum-sudangrass cover crop, dry biomass of broadleaf weeds was lower by 74% and 56% in June and July, respectively, compared with preceding sunn hemp. Smooth pigweed, common lambsquarters, and hairy galinsoga (Galinsoga quadriradiata) were the weed species most consistently affected by preceding sorghum-sudangrass cover crop with biomass decreased by up to 80%, 78%, and 64%, respectively. Thus, it appears that sorghum-sudangrass can provide suppression of some broadleaf species over a relatively long period and is indicative of sorghum-sudangrass allelopathic activity. On the contrary, density and biomass of grassy weeds as well as commercial yield of transplanted cabbage were unaffected by the preceding cover crop. These results suggest that sorghum-sudangrass cover crop could be integrated to transplanted cole crop rotation for providing weed suppression benefits without altering crop yield in New Jersey organic vegetable cropping systems.

Cropping system and soil texture shape soil health outcomes and scoring functions

Inherent soil properties often define the soil's basic functions, but human management can have superimposing impacts on the quality of soil. It is therefore challenging to interpret Soil Health (SH) measurements in the context of a region's soils and cropping systems. We examined the effects of soil texture, a dominant inherent soil property, and cropping system on SH indicators for New York, USA soils. A dataset of 1,750 soil samples was analyzed for SH indicators including Soil Organic Matter (SOM), Permanganate-Oxidizable Carbon (POXC), Soil Respiration (Resp), soil protein (Protein), Available Water Capacity (AWC), Wet Aggregate Stability (WAS), surface and subsurface penetration resistance, and seven soil chemical properties. Measured physical and biological indicators were affected by both soil texture and cropping system. AWC measured on disturbed samples was mostly affected by texture (37.4% variance explained), while Resp, Protein, and WAS were mostly impacted by cropping system (11.7%, 14.7%, and 22.1% variance explained, respectively). POXC was equally affected by texture and cropping system. Pasture and Mixed Vegetable systems tended to have the highest biological and physical soil health, followed by Dairy Crop systems. Annual Grain and Processing Vegetable cropping systems tended to have the lowest soil health. The effects of cropping systems are presumably linked to differences in the carbon and nutrient balances and the amount of soil disturbance through tillage. New scoring functions based on soil texture classes and cropping systems were developed for New York State to facilitate interpretation of SH test results in the context of the production-specific environments.

Integrated management of living mulches for weed control: A review

AbstractLiving mulches are cover crops grown simultaneously with and in close proximity to cash crops. Advantages of living mulches over dead cover crops may include increased weed suppression, reduced erosion and leaching, better soil health, and greater resource-use efficiency. Advantages of living mulches over synthetic mulches may include enhanced agroecosystem biodiversity and suitability for a wider range of cropping systems. A major disadvantage of this practice is the potential for competition between living mulches and cash crops. The intensity and outcome of mulch-crop competition depend on agroecosystem management as well as climate and other factors. In this review, we consider the management of living mulches for weed control in field and vegetable cropping systems of temperate environments. More than 50 yr of research have demonstrated that mechanical or chemical suppression of a living mulch can limit mulch-crop competition without killing the mulch and thereby losing its benefits. Such tactics can also contribute to weed suppression. Mechanical and chemical regulation should be combined with cultural practices that give the main crop a competitive advantage over the living mulch, which, in turn, outcompetes the weeds. Promising approaches include crop and mulch cultivar selection; changes to planting time, density, and planting pattern; and changes to fertilization or irrigation regimes. A systems approach to living mulch management, including an increased emphasis on the interactions between management methods, may increase the benefits and lower the risks associated with this practice.

Effects of biochar-based fertilizer on nitrogen use efficiency and nitrogen losses via leaching and ammonia volatilization from an open vegetable field.

It is essential for the sustainable development of agriculture to enhance nitrogen use efficiency (NUE) of crop plants by increasing yield and reducing nitrogen (N) losses. Biochar-based fertilizer (BF) has received increasing attention because of its full play to the advantages of chemical compounds with sufficient N and less N loss risk with good adsorption characteristics, but this potential was seldom reported for open-field vegetable crops, NUE of which were significantly lower than cereal crops. A field trial was conducted to investigate the efficacy of BF on NUE in vegetable cropping system by comparison with chemical fertilizer (CF) and partial substitution of organic fertilizers to chemical fertilizers (COF). The yield, plant N uptake, residual soil mineral N, and N losses via leaching and ammonia volatilization from an open vegetable (water spinach, Ipomoea aquatica L.) field were analyzed. The results indicated that BF treatment had significantly higher yield, plant N uptake, and NUE (agronomic efficiency and recovery efficiency as the NUE indicators), compared with those of CF and COF treatments. N losses via leaching were respectively accounted for 53.30%, 37.74%, and 33.39%; and N losses via ammonia volatilization were respectively accounting to 1.13%, 0.78%, and 1.54% of N fertilizer applied (at a rate of 200 kg N/ha) in CF, COF, and BF treatments. Despite the increasing ammonia volatilization due to the alkalinity of biochar, BF treatment significantly enhance NUE by increasing N uptake by water spinach and minimizing N losses via leaching. This study suggested that BF could serve as a promising slow-release N fertilizer for sustainable N management in field vegetable production and provided critical information for the development and dissemination of BF management guidelines.

Significant soil degradation is associated with intensive vegetable cropping in a subtropical area: a case study in southwestern China

Abstract. Within the context of sustainable development, soil degradation driven by land use change is considered a serious global problem, but the conversion from growing cereals to vegetables is a change that has received limited attention, especially in subtropical regions. Here, we studied the effects of the conversion from paddy rice to an oilseed rape rotation to vegetable production in southwestern China on soil organic carbon (SOC), total nitrogen (TN), the C/N ratio, pH, phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) based on face-to-face farmer surveys and soil analysis. In the vegetable cropping system, fertilizer application often exceeds the crop demand or levels recommended by the local extension service several times over. Thus, the crop use efficiency of N, P, K, Ca, and Mg was only 26 %, 8 %, 56 %, 23 %, and 28 %, respectively. In the vegetable cropping system studied, SOC, C stock, TN, and N stock were decreased significantly due to low organic inputs from crop residues and high tillage frequency. Furthermore, the soil C/N ratio decreased slightly; available P (AP) in the topsoil increased by 1.92 mg kg−1 for every 100 kg ha−1 of P surplus, and the critical levels of AP and CaCl2-soluble P in P leaching were 104 and 0.80 mg P kg−1. Besides, compared to the current paddy–rape rotation system, a clear trend of soil acidification was observed in the vegetable fields. However, increasing the contents of soil Ca and Mg significantly alleviated topsoil acidification, with the effect increasing over time. Given our findings, the potential benefits of conservation agricultural practices, integrated soil–crop system management strategies, and agricultural technology services for recovering the degraded soil and improving the vegetable productivity are discussed here.

Molecular gut content analysis indicates the inter- and intra-guild predation patterns of spiders in conventionally managed vegetable fields.

Inter‐ and intra‐guild interactions are important in the coexistence of predators and their prey, especially in highly disturbed vegetable cropping systems with sporadic food resources. Assessing the dietary range of a predator taxon characterized by diverse foraging behavior using conventional approaches, such as visual observation and conventional molecular approaches for prey detection, has serious logistical problems. In this study, we assessed the prey compositions and compare the dietary spectrum of a functionally diverge group of predators—spiders—to characterize their trophic interactions and assess biological control potential in Brassica vegetable fields. We used high‐throughput sequencing (HTS) and biotic interaction networks to precisely annotate the predation spectrum and highlight the predator–predator and predator–prey interactions. The prey taxa in the gut of all spider families were mainly enriched with insects (including dipterans, coleopterans, orthopterans, hemipterans, and lepidopterans) with lower proportions of arachnids (such as Araneae) along with a wide range of other prey factions. Despite the generalist foraging behavior of spiders, the community structure analysis and interaction networks highlighted the overrepresentation of particular prey taxa in the gut of each spider family, as well as showing the extent of interfamily predation by spiders. Identifying the diverse trophic niche proportions underpins the importance of spiders as predators of pests in highly disturbed agroecosystems. More specifically, combining HTS with advanced ecological community analysis reveals the preferences and biological control potential of particular spider taxa (such as Salticidae against lepidopterans and Pisauridae against dipterans), and so provides a valuable evidence base for targeted conservation biological control efforts in complex trophic networks.

Black Soldier Fly-Composted Organic Fertilizer Enhances Growth, Yield, and Nutrient Quality of Three Key Vegetable Crops in Sub-Saharan Africa.

Worldwide, French beans (Phaseolus vulgaris L.), tomato (Solanum lycopersicum L.), and kales (Brassica oleracea L. var. acephala) are considered economically important food crops. There is a rapid decline in their yield due to severe soil degradation. Thus, high commercial fertilizer inputs are crucial, though they remain expensive and inaccessible to resource poor farmers. We investigated the comparative performance of composted black soldier fly frass fertilizer (BSFFF), conventionally composted brewer's spent grain (BSG), commercial organic fertilizer (Evergrow), and mineral [nitrogen, phosphorus, and potassium (NPK)] fertilizer on growth, yield, N use efficiency, and nutritional quality (crude protein, crude fiber, crude fats, ash, and carbohydrate concentrations) of tomatoes, kales, and French beans under greenhouse and open-field conditions for two seasons. The fertilizers were applied at rates equivalent to 371 kg of N ha−1. For each crop, the plots were treated with sole rates of BSFFF, BSG, Evergrow, and NPK to supply 100% of the N required. Additional treatments included a combination of BSFFF and NPK, and BSG and NPK so that each fertilizer supplies 50% of the N required. The control treatment consisted of unfertilized soil. Results show that vegetable yields achieved using a combination of BSFFF and NPK were 4.5, 2.4, and 5.4-folds higher than the yield from the control treatment for tomatoes, kales, and French beans, respectively. The combined application of BSFFF and NPK produced 22–135%, 20–27%, and 38–50% higher yields than sole NPK for tomatoes, kales, and French beans, respectively, under both greenhouse and open-field conditions. The highest agronomic N use efficiency was achieved in sole BSFFF-treated plots compared to sole BSG and Evergrow. The N taken up by the vegetables was significantly higher when BSFFF and NPK were integrated. Vegetables grown using a combination of BSFFF and NPK had the highest crude protein and ash concentrations. Our findings demonstrate that the integration of BSFFF and NPK in vegetable cropping systems at the recommended rate of 1.24 t ha−1 BSFFF and 322 kg ha−1 NPK would improve soil health, boost yield, and nutritional quality of vegetable crops.

Opportunities to improve nitrogen use efficiency in an intensive vegetable system without compromising yield

Intensive vegetable cropping systems rely heavily on nitrogen (N) inputs from multiple synthetic and organic fertilizer applications. The majority of applied N is lost to the environment through numerous pathways, including as nitrous oxide (N2 O). A field trial was conducted to examine the opportunities to reduce N input in an intensive vegetable system without compromising yield. Treatments applied were control (no N), manure (M, 408kg N ha-1 from chicken manure), grower practice (GP, 408kg N ha-1 from chicken manure + 195kg N ha-1 from fertilizer), and 2/3 GP (two-thirds of the total N input in GP), all with and without 3,4-dimethylpyrazole phosphate (DMPP). Nitrogen recovery in the GP treatment was determined using 15 N-labeled fertilizer. Using only manure significantly lowered celery (Apium graveolens L.) yield and apparent N use efficiency (ANUE) compared with GP. Reducing N input by one-third did not affect yield or ANUE. Use of DMPP increased ANUE despite no yield improvement. More than 50% of the applied N in the GP treatment was lost to the environment, with almost 10kg N ha-1 emitted as N2 O over the season, which was 67 times more than from the control. Reducing the N input by one-third or using manure only reduced N2 O emissions by more than 70% relative to GP. This study shows that there is a clear opportunity to reduce N input and N2 O emissions in high-fertilizer-input vegetable systems without compromising vegetable yield.

Exploring management strategies to improve yield and mitigate nitrate leaching in a typical radish field in northern China

It is currently uncertain whether process-based models are capable of assessing crop yield and nitrogen (N) losses while helping to investigate best management practices from vegetable cropping systems. The objectives of this study were to (1) calibrate and evaluate the Denitrification-Decomposition (DNDC) model in simulating crop growth and nitrate leaching in a typical field radish system; (2) optimize management practices to improve radish yield and mitigate nitrate leaching under 20-year climate variability. A five-season in-situ field experiment of spring and autumn radish in northern China was established in the autumn of 2017 and measurements of radish yield, N uptake, soil temperature, soil moisture, drainage, and nitrate leaching were obtained under different N usage. DNDC overall demonstrated “good” to “excellent” performance in simulating radish yield, total biomass, N uptake, and soil temperature across all treatments (6.4% ≤ normalized root mean square error (nRMSE) ≤ 15.5%; 0.12 ≤ Nash-Sutcliffe efficiency (NSE) ≤ 0.88; 0.80 ≤ index of agreement (d) ≤ 0.97). DNDC generally exhibited “fair” performance in estimating soil moisture and drainage (10.9% ≤ nRMSE ≤ 27.2%; −0.18 ≤ NSE ≤ 0.37; 0.69 ≤ d ≤ 0.82) and “good” performance when predicting nitrate leaching (12.4% ≤ nRMSE ≤ 26.7%; −0.59 ≤ NSE ≤ 0.51; 0.68 ≤ d ≤ 0.90). Sensitivity analyses demonstrated that optimized management practices (planting dates, irrigation amount, fertilization rate and timing) could substantially reduce N usage by 40%–50%, irrigation amount by 33%–50%, and nitrate leaching by 86%–95% compared to farmers’ practice in radish planting system. This study indicated that a modelling method is helpful for evaluating the biogeochemical effects of management alternatives and identifying optimal management practices in radish production systems of China.