Vegetable Cropping Systems Research Articles

Impact of biochar application on the productivity of a temperate vegetable cropping system

ABSTRACTFew studies have investigated the potential of biochar in supporting cool temperate horticultural systems with fertile soils. We examined the effects of applying 10 t ha−1 of blue mallee (Eucalyptus polybractea) biochar in combination with fertiliser rate treatments (either full or half the regional recommended rate) on crop yield, yield parameters and soil properties of a cool temperate vegetable cropping system on a red Ferrosol. Biochar amendment did not improve crop yield or other yield parameters of cauliflower, peas and broccoli crops. Similarly, soil parameters including nitrate and ammonium were unaffected by biochar treatment. We suggest the lack of biochar effect on crop and soil parameters was related to the inherent chemical fertility and structural robustness of Ferrosols, which may have mitigated any potential benefits from biochar amendment. Our results demonstrate that biochar application may not bring significant soil quality and crop productivity improvements to high-input agricultural systems.

Productivity and economic benefits of coconut based vegetable cropping systems under central dry zone of Karnataka

<p>Coconut based cropping systems with vegetables i.e., okra-fallow (2012-13) and tomato-fallow (2013-14), green manure-cucumber,<br />baby corn-gherkin and coconut monocropping as control with four integrated nutrient management (INM) practices viz., inorganic<br />fertilizer alone (100%), 5 ton farm yard mannure (FYM)+75% NPK+25% N by vermicompost (VC), 5 ton FYM+50% NPK+25%<br />N by vermicompost+25% N by composted coir pith (CCP)+ Indian Institute of Horticulture Research (IIHR) micronutrient spray<br />and 5 ton FYM+50% N by vermicompost+50% N by CCP+vermiwash spray+Azatobacter were evaluated at HRS, Arsikere,<br />Karnataka during the year 2012 to 2014 by adopting factorial RBD with five replications. All the vegetable crops gave the highest<br />yield under integration of organic and inorganic manure treatments, viz., 5 tonne FYM+74% NPK +25% N by VC and 5 ton<br />FYM+50% NPK+25% N by vermicompost+25% N by CCP+IIHR micronutrient spray, whereas the lowest vegetables yield was<br />noticed with 5 ton FYM+50% N by vermicompost+50% N by CCP + vermiwash spray + Azatobacter. Cropping sequence, baby<br />corn-gherkin resulted in the highest coconut equivalent yield of intercrops and cropping system (33,548 nuts ha-1 and 44,414 nuts<br />ha-1, respectively). Pooled economic analysis indicated that, okra-fallow and tomato-fallow sequence resulted in significantly<br />higher net income (` 4,03,551 ha-1) compared to other sequences and it was on par with baby corn-gherkin sequence<br />(` 3,60,365 ha-1).</p>

Enhancing multifunctional benefits of living mulch in organic vegetable cropping systems

Over the last several decades, agriculture in industrialized countries experienced a significant intensification as a result of the diffusion of mechanization, the widespread use of genetically improved genotypes, and the large-scale use of off-farm inputs, mainly in the form of fossil fuel energy and synthetic fertilizers and pesticides. Under the pressure of the growing agro-industrial sector, which has been oriented to promote models based on large volumes and long-distance supply chains, intensification was accompanied by progressive specialization of farms and cropping systems (Ratnadass et al., 2012). Indeed, the reduction of diversity at the field, farm, and territory level, a result of a low number of crops, the shortening of crop rotations, and a decrease in the number of cultivated genotypes, is becoming evident in many agro-environments in developed countries.

Changes in Soil Organic Carbon After Five Years of Biowaste Compost Application in a Mediterranean Vegetable Cropping System

Biowaste compost can influence soil organic matter accumulation directly or indirectly. A 5-year experiment was conducted to assess the influence of biowaste compost on the process of soil aggregation and soil organic carbon (SOC) accumulation in a Mediterranean vegetable cropping system. The study involved four treatments: biowaste compost (COM), mineral NPK fertilizers (MIN), biowaste compost with half-dose N fertilizer (COMN), and unfertilized control (CK). The SOC stocks were increased in COM, COMN, and MIN by 20.2, 14.9, and 2.4 Mg ha−1 over CK, respectively. The SOC concentration was significantly related to mean weight diameter of aggregates (MWD) (P < 0.05, R2 = 0.798 4) when CK was excluded from regression analysis. Compared to CK, COM and COMN increased the SOC amount in macroaggregates (> 250 μm) by 2.7 and 0.6 g kg−1 soil, respectively, while MIN showed a loss of 0.4 g kg−1 soil. The SOC amount in free microaggregates (53–250 μm) increased by 0.9, 1.6, and 1.0 g kg−1 soil for COM, COMN, and MIN, respectively, while those in the free silt plus clay aggregates (< 53 μm) did not vary significantly. However, when separating SOC in particle-size fractions, we found that more stable organic carbon associated with mineral fraction < 53 μm (MOM-C) increased significantly by 3.4, 2.2, and 0.7 g kg−1 soil for COM, COMN, and MIN, respectively, over CK, while SOC amount in fine particulate organic matter (POM) fraction (53–250 μm) increased only by 0.3 g kg−1 soil for both COM and COMN, with no difference in coarse POM > 250 μm. Therefore, we consider that biowaste compost could be effective in improving soil structure and long-term C sequestration as more stable MOM-C.

Effect of anaerobic soil disinfestation on the bacterial community and key soilborne phytopathogenic agents under walnut tree-crop nursery conditions

Background and aims Anaerobic Soil Disinfestation (ASD) is a chemical-independent approach to managing soilborne phytopathogens. While it has been demonstrated that ASD can suppress phytopathogens in vegetable cropping systems, it has not been examined for control of tree-crop diseases under nursery conditions. Here we report on the potential of using ASD to manage soilborne populations of Agrobacterium tumefaciens and Pythium ultimum under walnut rootstock nursery conditions and compared the efficacy of ASD with the chemical fumigant Telone-C35.

Eco-efficient choice of cropping system for reducing nitrate-N leaching in an agricultural watershed

Eco-efficiency analysis framework was used to evaluate joint economic and environmentally optimal N application rates for alternative cropping systems managed in a watershed in Atlantic Canada. Eco-efficiency indexes were estimated as the ratio of economic returns from N fertilizer application to groundwater-N leaching associated with crop production. Trade-offs between crop yield and associated reduction in groundwater-N leaching were also estimated. Data for the analysis were generated using the soil and water analysis tool modeling, and allowed for evaluating crop yield and groundwater-N leaching effects for a given crop in rotations assumed to be managed at varying N fertilizer application rates. The cropping systems evaluated included: (i) corn-based cropping systems involving corn–corn–alfalfa–alfalfa–alfalfa (CCAAA, and CCCAA) rotations; (ii) potato-based cropping systems involving potato–corn–barley–potato–corn (PCBPC and PBWPC); and (iii) vegetable-horticulture cropping system involving potato–winter wheat–carrot–corn. Cropping systems were compared under conventional tillage (CT) and no-till (NT) systems. Estimated eco-efficient N fertilizer rates were substantially lower than current provincial nutrient management plan (NMP)-recommended rates, and estimated maximum economic rate of nitrogen fertilizer. However, the actual amounts depended on the crop and rotation system. CCAAA-CT was the eco-efficient choice of rotation system among the corn-based cropping systems considered. Similarly, PCBPC-CT was the eco-efficient choice among the potato-based production systems. In addition, when the NMP-recommended N rate was replaced by the eco-efficient rate for the vegetable horticulture cropping system, the eco-efficient cropping system shifted from a rotation involving CT to a NT system.

Dissipation Kinetics of Chlorpyrifos in Soils of a Vegetable Cropping System under Different Cultivation Conditions

Dissipation kinetics of chlorpyrifos in the near-neutral paddy soils of a vegetable cropping system under greenhouse, screenhouse and field conditions was studied using a rapid analytical method. The recoveries of chlorpyrifos were between 86.5% and 105.5% with relative standard deviations for repeatability between 6.6% and 9.1% at fortification levels of 0.01, 0.1 and 1 mg/kg in the soil. The limit of detection of the method was 0.004 mg/kg and the limit of quantification was found to be 0.01 mg/kg. The dissipation rates of chlorpyrifos followed the first-order kinetics and the half-life was 6.96, 6.04 and 5.20 days in the soil under greenhouse, screenhouse and field conditions, respectively. The dissipation rates of chlorpyrifos in the soil varied with different cultivation conditions. Chlorpyrifos in the soil dissipated slower in a greenhouse and screenhouse than in the open field, which was likely attributed to the hermetic environment in the greenhouse and screenhouse.

Use of the Nitrogen Index to assess nitrate leaching and water drainage from plastic-mulched horticultural cropping systems of Florida

Water quality in Florida is significantly impacted by nitrate (NO3-N) leaching losses from agriculture in a large part of the state. Horticultural crops are planted across large areas of Florida on coarse sandy soils with low soil water retention and soil organic matter, increasing the potential for NO3-N leaching. Nitrate leaching losses from the root zone of vegetable cropping systems can negatively impact groundwater. New tools such as the Nitrogen Index (N-Index) are able to quickly assess N use efficiency and losses via NO3-N leaching from agricultural systems. Furthermore, the N-Index provides technical information about N losses pathways tied to agricultural management practices with a great level of confidence; this information has been used by researchers, growers and policymakers as a decision support system. However, the current version of the N-Index that has been used for different field crops has not been calibrated to be used in plastic-mulched horticultural cropping systems. The aim of this work was to calibrate and validate the N-Index for plastic-mulched horticultural cropping systems of Florida. This study found that the N-Index tool accurately identified and ranked the risk of N losses in the evaluated horticultural systems. The N-Index was calibrated for Florida's plastic-mulched horticultural cropping systems using a sensitivity analysis. The adjusted N-Index was validated using compiled data of vegetables grown under plastic mulching systems during three consecutive seasons. Results from these studies suggest that the N-Index can be an easy-to-use tool capable of assessing nitrogen management practices for vegetable systems. The tool can be used to guide nutrient managers in the implementation of best nitrogen management practices that could contribute to reduced NO3-N leaching losses from vegetable systems in Florida, contributing to a smaller environmental footprint and conservation of water quality.

Quantitative Relationship Between Nitrous Oxide Emissions and Nitrogen Application Rate for a Typical Intensive Vegetable Cropping System in Southeastern China

To explore the mechanism underlying the relationship between nitrous oxide (N2O) emissions and different nitrogen (N) application rates, we conducted a 2‐year‐round field experiment comprising seven vegetable crop seasons by using static chamber‐gas chromatographic techniques in a continuously cultivated vegetable cropping system in Southeastern China. The results showed that N application significantly affected the N2O emissions. The cumulative N2O emissions amounted to 16.9 ± 1.9, 25.2 ± 2.2, 30.0 ± 1.9, 36.7 ± 1.5, and 48.1 ± 2.2 kg N ha−1 y−1 for the five N application rates at 0, 370, 740, 1110, 1480 kg N ha−1 y−1, respectively. Both linear and exponential relationship was observed between cumulative N2O emissions and N application rates. The emission factors ranged from 1.8 ± 0.1 to 2.3 ± 0.6% and averaged 2.0 ± 0.3%. The treatment receiving 2/3 of the conventional N fertilizer amount led to the lowest yield‐scaled N2O emissions. Therefore, according to this study the recommended N application rate should be reduced by one‐third for N2O mitigation while enhancing vegetable production in Southeastern China.

Linking chemical and biochemical composition of plant materials to their effects on N2O emissions from a vegetable soil

The magnitudes of nitrogen (N) mineralisation and nitrous oxide (N2O) emissions after the application of plant materials strongly depend on their quality. Despite the existence of some studies in this field, little is known about the underlying mechanisms and regulating factors of these processes, particularly for vegetable cropping systems. In this study, ten typical vegetable and/or vegetable farming rotation plant materials were finely ground, incorporated into the soil and incubated at 25 °C under fluctuating moisture conditions of 55–85% water-filled pore space (WFPS) without N (-N) or with N (+N) addition (100 mg N kg−1 soil as urea). The applied plant materials were characterised using solid state 13C nuclear magnetic resonance (NMR) spectroscopy and wet-chemical analysis. The dynamics of soil mineral N accumulation and N2O emissions were monitored over 169 days. Under the -N treatment, plant materials with total N (TN) contents ≥ 27 mg g−1 dry matter produced significantly higher cumulative N2O emissions than those with TN contents < 27 mg g−1 in the first 105 days of incubation. However, there was no significant difference in cumulative N2O emissions between these two groups at the end of the experiment due to higher N2O emissions for plant materials with TN contents <27 mg g−1 during the later stage of the incubation. Under the +N treatment, application of plant materials consistently increased the cumulative N2O emissions by the end of the incubation compared with the urea only treatment; although a few plant materials resulted in lower or similar N2O emissions in the initial 2–4 weeks. During the entire incubation, plant materials with high TN contents generally produced higher cumulative N2O emissions than others in the +N treatment. Stepwise regression analysis indicated a significant correlation between cumulative N2O emissions and TN, cellulose, lignin, O-aryl C and carbonyl C contents of the plant materials; TN content was the main regulating factor among all chemical and biochemical indices.

Use of biological indicators of soil health to estimate reactive nitrogen dynamics in long-term organic vegetable and pasture systems

Diverse crop rotations, cover crops and the possibility of integrating livestock make organic systems potentially more sustainable than other agroecosystems. Lower reactive nitrogen (N) in organic systems minimizes the potential for N losses. However, addition of organic manures and residues containing mineralizable N and carbon (C) have the potential to enhance nitrous oxide (N2O) emissions. We conducted a 39 d laboratory incubation to assess key microbiological drivers controlling nitrification and denitrification in long-term organic agroecosystems during simulated freeze-thaw cycles. Soils were collected from two annual organic vegetable systems receiving 1) mixed-compost, or 2) broiler litter and 3) an organic perennial pasture system cropped to vegetables every third year. Soil microcosms amended with 15N labelled sugar beet residue or unamended were maintained at 40, 60 and 80% of water filled pore space (WFPS). Significant N2O was emitted (4287–6138 μg kg−1soil) via denitrification from amended soil microcosms at 3 °C and 80% WFPS. Archaeal (AOA) and bacterial (AOB) nitrifier amoA gene copies were affected by temperature and reactive N species during freeze-thaws. Long-term organic vegetable cropping systems receiving mixed-compost additions had the potential to accumulate C and immobilize excess reactive soil N (particularly nitrates) thereby improving soil health and reducing N2O emissions.

Winter tillage impacts on soil organic carbon, aggregation and CO2 emission in a rainfed vegetable cropping system of the mid–Yunnan plateau, China

The mid–Yunnan plateau is one of the major regions for the production of vegetables in China, but intense management practices have led to soil degradation and amplified greenhouse–gas emissions. Understanding management effects on soil organic carbon dynamics and structural stability can aid to improve vegetable cropping systems sustainability in this region. In the present study, we evaluated the effect of seasonal tillage alterations (non–winter–tillage [NWT] and winter–tillage [WT]) on soil (0–10cm) organic carbon (SOC) retention, soil aggregate stability, aggregate–associated C concentrations and CO2 emission in a clay loam soil. Results indicated after 2 years that the plots under NWT had nearly 4% higher total SOC content and 9% higher proportion of large macro-aggregates (>2mm) compared with WT plots in the 0–5cm layer. Greater SOC and labile C within large macro–aggregates in the plots under NWT compared with WT were also observed in the surface layer only. Soil CO2 emission rates were significantly greater in the WT plots than in the NWT plots during the dry season, but did not differ significantly between the WT and NWT plots during the rainy season. Our results demonstrated that the adoption of NWT should be a more sustainable management option than the traditional winter tillage for the maintenance of soil C and reduction of carbon dioxide emission in the rainfed vegetable cropping system of the mid–Yunnan plateau.

Effects of organic fertilizer on net global warming potential under an intensively managed vegetable field in southeastern China: A three-year field study

Organic fertilizer may not only improve soil quality but may also contribute to climate protection by increasing carbon sequestration in agricultural ecosystems. A 3-yr study was conducted with ten consecutive vegetable crops in intensively managed vegetable cropping systems in southeastern China to examine the effects of organic fertilizer application (ORGA) on net global warming potential (net GWP) after accounting for carbon dioxide equivalent emissions from all sources including methane (CH4) and nitrous oxide (N2O) emissions, agrochemical inputs and farm operations and sinks (i.e., soil organic carbon (SOC) sequestration derived from the net ecosystem carbon budget). Results indicated that ORGA significantly increased ecosystem respiration by 13.9% without obvious effects on CH4 and N2O emissions as compared to local conventional chemical fertilization (CHEM). The SOC sequestration rates during the 3-year observation period were estimated at −0.52 t C ha−1 for the control, −0.42 t C ha−1 for the CHEM plot and 0.27 t C ha−1 for the ORGA plot, respectively, and thus contributed significantly to the net GWP. Overall, compared with CHEM, the ORGA significantly decreased net GWP and greenhouse gas intensity by 15.3% and 27.4%, respectively. Our findings suggest that higher yields and lower greenhouse gas intensities and carbon costs can be achieved by substituting chemical nitrogen fertilizers with organic fertilization strategies.

Yield, product quality and energy use in organic vegetable living mulch cropping systems: research evidence and farmers’ perception

AbstractThe effects of living mulch (LM) introduction and management strategies on cash crop yield, product quality and energy use were studied in a wide range of European vegetable cropping systems, climatic and soil conditions, as well as species of LM grown as agro-ecological service crops. Nine field experiments were carried out in research stations and commercial farms located in Denmark, Germany, Italy and Slovenia. Farmers’ perception of the feasibility and applicability of the LM technique was also assessed.The results demonstrated that the LM systems with a substitutive design can be effectively implemented in vegetable production if the value of the ecological services (positive externalities) delivered by LM can counterbalance the yield loss due to the cash crop density reduction. The crop density of the system and the length of the period in which the LM and cash crop coexist are oppositely related both for competition and yield. Moreover, if an additive design is used, the LM should be sown several weeks after the cash crop planting. Overall, different cash crop genotypes (i.e., open pollinated/local cultivars in comparison with the hybrids) performed similarly. Use of human labor (HL) and fossil fuel (FF) energy slightly increased in LM systems (7%), and there was a shift in the proportion of FF and human energy consumption. The farmers’ acceptance of the LM techniques was quite high (75% of the interviewed sample), even though their critical considerations about yield quality and quantity need consideration in future research and practical implementation of LM systems.

Effect of the nitrification inhibitor (DMPP) on soil nitrous oxide emissions and yield in a lettuce crop in Queensland, Australia

The use of nitrification inhibitors, in combination with ammonium based fertilisers, has been promoted recently as an effective method to reduce nitrous oxide (N2O) emissions from fertilised agricultural fields, whilst increasing yield and nitrogen use efficiency. However, to date no data is available on the use of nitrification inhibitors in sub-tropical vegetable systems. A field experiment investigated the effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on N2O emissions and yield from lettuce production in sub-tropical Australia. Soil N2O fluxes were monitored continuously over 120 days with a fully automated system. Measurements were taken from three subplots for each treatment within a randomized complete blocks design. Cumulative N2O emissions over the 120 day observation period amounted to 191, 93 and 46 g-N ha-1 in the conventional fertiliser (CONV), the DMPP treatment and the zero fertiliser (0N) respectively. Consequently, the use of DMPP decreased seasonal N2O emissions by more than 50%, but had no significant impact on lettuce yield. The temporal variation of N2O fluxes showed only low emissions over the lettuce cropping period in all treatments, but significantly elevated emissions were observed in the CONV fertilized and DMPP treatment postharvest, following lettuce residues being incorporated into the soil. This study highlights that DMPP can substantially reduce N2O emissions from vegetable cropping systems. It also emphasizes that N input from vegetable crop residues incorporated into the soil after harvest can lead to substantially elevated N2O emission. Hence, in such systems post-harvest emissions need to be in the centre of attention for developing N2O mitigation strategies.

Summer Cover Crops and Lettuce Planting Time Influence Weed Population, Soil Nitrogen Concentration, and Lettuce Yields

Cover crops can be used as a sustainable weed management tool in crop production systems. Cover crops have the ability to suppress weeds, reduce soil erosion, increase soil organic matter, and improve soil physical, chemical, and biological properties. In the north-central region of the United States, including Iowa, much cover crop research has been conducted in row crop systems, mainly with corn (Zea mays) and soybean (Glycine max) where cover crops are planted at the end of the growing season in September or October. There is little information available on the use of cover crops in vegetable cropping systems, particularly on the use of summer cover crops for fall vegetable production. The choice of the cover crop will significantly impact the entire fall vegetable production enterprise. Vegetable growers need information to identify the right cover crop for a particular slot in the cropping system and to understand how cover crops would affect weed suppression, soil properties, and successive vegetable crop yield. The time interval between cover crop termination and vegetable planting critically affects the growth and successive yield of the vegetable crop. This study investigated how short-duration summer cover crops impact weed suppression, soil properties, and ‘Adriana’ lettuce (Lactuca sativa) yield. The study also examined appropriate planting times of lettuce transplants after soil incorporation of cover crops. The experimental design was a randomized complete block split-plot design with four replications. Whole plots consisted of cover crop treatments: ‘Mancan’ buckwheat (Fagopyrum esculentum), ‘Iron &amp; Clay’ cowpea/southernpea (Vigna unguiculata), black oats (Avena strigosa), ‘Grazex II’ sorghum-sudangrass (Sorghum bicolor ssp. drummondii), and a control (no-cover crop) where weeds were left to grow unchecked. The subplot treatment consisted of two lettuce transplanting times: planted immediately or 8 days after cover crop soil incorporation. Fall-planted butterhead lettuce was used. Data were collected on cover crop biomass, weed biomass, soil nutrient concentration, lettuce growth, and yield. All cover crops significantly reduced weed biomass during the fallow period as compared with the control treatment. Highest degree of weed suppression (90% as compared with the no-cover crop control treatment) was provided by buckwheat. Southernpea, a legume, increased soil nitrogen (N) concentration and contributed to higher lettuce yield and improved quality. Southernpea also enhanced lettuce growth and led to an earlier harvest than other treatments. Sorghum-sudangrass showed evidence of detrimental effects to the marketable lettuce crop. This was not due to N immobilization but presumably due to alleopathic properties. There is no clear pattern within any cover crop treatment that lettuce planting time following cover crop termination affects plant growth; however, planting early or soon after cover crop incorporation ensures more growing degree days and daylight, thus leading to timely harvest of a higher quality product. This study demonstrates that cover crops can successfully be integrated into vegetable cropping systems; however, cover crop selection is critical.

Tillage System and Cover Crop Management Impacts on Soil Quality and Vegetable Crop Performance in Organically Managed Production in Tennessee

Research is lacking on the impact of alternative reduced tillage (RT) systems on vegetable crop performance and soil quality, especially in organic production systems, where weed control cannot rely on synthetic herbicides. A 2-year field study was implemented in Aug. 2010 in Knoxville, TN, to evaluate cover crop–based systems for organic vegetable production either with or without spring tillage. Treatments, all organically managed, included 1) Till (+ACC), spring tillage of a winter cover crop with aboveground cover crop biomass (ACC) retained and soil covered by polyethylene mulch; 2) Till (−ACC), spring tillage of a winter cover crop with aboveground cover crop biomass (ACC) removed before tillage and soil covered by polyethylene mulch; and 3) RT system with no spring tillage and mechanically terminated winter cover crop residue on the soil surface. Vegetable crops of eggplant (Solanum melongena L.) and watermelon [Citrullus lanatus (Thunb.) Matsum. et Nakai] were planted in 2011 and 2012, respectively. Crop yield, cover crop biomass accumulation, soil N and C dynamics, and weed density were assessed. Marketable eggplant yield and marketable watermelon yield did not differ among treatments, but weed density was higher in the RT system. Measures of soil quality after 2 years of the study indicated that particulate organic matter-carbon (POM-C) and -nitrogen (POM-N) were highest in the RT treatment, a significant increase as compared with values at the beginning of the study. As a measure of the active fraction of soil organic matter, this indicates that the RT system may best maintain and improve soil quality in similar regional organic vegetable cropping systems. As indicated by measures of soil quality and crop yield, removal of aboveground cover crop biomass did not negatively impact the Till (−ACC) system as compared with the Till (+ACC).

Combined agro-ecological strategies for adaptation of organic horticultural systems to climate change in Mediterranean environment

Agricultural biodiversity and related agro-ecological measures could play a crucial role in the agro-ecosystems adaptation to climate changes, thus sustaining crop production. The objective of this study was to assess the suitability (and the best combination) of agro-ecological techniques as potential resilience strategies in organic horticultural systems in a Mediterranean environment. A long-term experimental device called MITIORG (Long-term climatic change adaptation in organic farming: synergistic combination of hydraulic arrangement, crop rotations, agro-ecological service crops and agronomic techniques) is set-up at Metaponto (MT), testing the following agro-ecological measures as well as organic and conservation farming best practices: i) hydraulic arrangement by a kind of ridge-furrow system; ii) cash crop rotations; iii) agro-ecological service crops (ASC) introduction; iv) ASC termination techniques (green manure vs roller crimper); and v) organic fertilisation. The research here reported was carried out during the 2014-2015 season in the MITIORG device, on a rotation of cauliflower (Brassica oleracea L.) and tomato (Solanum lycopersicum L.) crops. A detailed description of the scientific cognitive process that led to setup of the device, its components explanation, as well as preliminary yield results are reported. The outcomes suggest that organic vegetable cropping systems, designed following agro-ecological principles, are able to sustain yield of cash crops in rotation, in spite of changes in temperature and rainfall of the study site. Experimental data available in the next years will allow a deeper integrated analysis of the manifold effects of agro-ecological measures on horticultural systems.

Global Warming Potential in an Intensive Vegetable Cropping System as Affected by Crop Rotation and Nitrogen Rate

Greenhouse gas emissions from vegetable production systems contribute to climate change, but the impact of nitrogen (N) rates and crop rotation on global warming potential (GWP) is not well documented. A field experiment was conducted to estimate the sum of GWP (mGWP) and yield‐scaled GWP in an intensive vegetable cropping system. The study included the traditional rotation of celery‐tomato‐lettuce (Rt) and the modified rotation of bur clover‐tomato‐lettuce (Rm), and each with four fertilizer N options (control, manure‐N, optimum, and conventional N). The nitrous oxide emission rates were 6.87 and 10.24 kg N ha−1, and the mGWP values were 27.9 and 31.8 MgCO2‐eq ha−1 per year from the optimum and conventional N plots under the traditional rotation, respectively. The change from the traditional to modified rotation reduced N input by 25%, N2O emissions by 24%, and mGWP by 14% but increased the net economic benefit by 33% under the optimized N application rate in the intensive vegetable cropping system. The trends of yield‐scaled GWP from different N rates and vegetable crop rotations were similar to the mGWP. This study proved that optimizing vegetable crop rotation by including legumes and adjusting N application rates simultaneously can reduce global warming potential while maintaining agricultural economic benefit.

Higher flexibility in input N:P ratios results in more balanced phosphorus budgets in two long-term experimental agroecosystems

Inefficient phosphorus (P) use in intensive agriculture is common in both organic and conventional systems, resulting in P over-application and soil P build-up. Increasing crop P removal and P recycling within farming systems (e.g., via cover crops) and reducing P inputs lower P surpluses, resulting in more balanced P budgets. Lowering P inputs to reduce soil P surpluses is easier with mineral fertilizers for which nitrogen (N) and P inputs can be decoupled, whereas reducing inputs of organic amendments with a constrained N:P stoichiometry (manures, composts) often results in N under-fertilization and lower yields. We computed farm-gate P budgets for several vegetable and grain cropping systems in two long-term California agricultural experiments that vary in terms of inputs (mineral fertilizers, organic fertilizers, manure, yard compost), cash crops (corn, wheat, tomato, broccoli, lettuce), cover crops (type, frequency) and cropping intensity (biennially, annually or biannually). In organic systems, using manure or compost resulted in high P surpluses, whereas using pelleted or liquid organic fertilizers with higher N:P ratios resulted in smaller P surpluses. Systems receiving mineral fertilizers were often very close to P balance when fertilized regularly. Grain rotations generally had small P deficits whereas vegetable rotations had P surpluses due to lower crop P removal and higher output N:P in vegetables. Phosphorus uptake by cover crops was important (12–25kg Pha−1), but their benefits to soil fertility will depend on the magnitude and timing of P release during residue decomposition. Overall, using organic nutrient sources with a constrained stoichiometry and low N:P ratios resulted in significant P surpluses, confirming the need to use complementary N sources such as N-fixation or N-rich fertilizers to balance P budgets.