Enhancing Vegetable Production Sustainability: Economic and Agronomic Benefits of Optimized Nitrogen Management Strategies

High levels of residual soil nitrate are typically present in cool-season vegetable fields in coastal regions of California in the fall, after the production of multiple crops over the course of the growing season. This nitrate is subject to leaching with winter rains when fields are left fallow. Although the benefits of growing nitrate scavenging cover crops on soil and water quality are well documented, the portion of vegetable production fields planted to winter cover crops in this region is low. Most growers leave their fields unplanted in bare-fallow beds because the risk of having too much cover crop residue to incorporate may delay late winter and early spring planting schedules. A possible strategy to derive benefits of a cover crop yet minimize the amount of residue is to kill the cover crop with an herbicide when biomass of the cover crop is still relatively low. To evaluate whether this strategy would be effective at reducing nitrate leaching, we conducted field studies in Winter 2010–11 (Year 1) and Winter 2011–12 (Year 2) with cereal rye ( Secale cereale ). Each trial consisted of three treatments: 1) Fallow (bare fallow), 2) Full-season (cover crop allowed to grow to full term), and 3) Partial-season (cover crop killed with herbicide 8 to 9 weeks after emergence). In Year 1, which received 35% more rainfall than the historical average during the trial, the Full-season cover crop reduced nitrate leaching by 64% relative to Fallow, but the Partial-season had no effect relative to Fallow. In Year 2, which received 47% less rainfall than the historical average during the trial, the Full- and Partial-season cover crops reduced nitrate leaching by 75% and 52%, respectively, relative to Fallow. The Full-season cover crop was able to reduce nitrate leaching regardless of yearly variations in the timing and amount of precipitation. Although the Partial-season cover crop was able to reduce leaching in Year 2, the value of this winter-kill strategy to reduce nitrate leaching is limited by the need to kill the crop when relatively young, resulting in the release of nitrogen (N) from decaying residues back into the soil where it is subject to leaching.

<p>Plastic-shed vegetable production system is becoming the main type of vegetable production in China, while excessive irrigation and fertilization input lead to significant N loss by leaching, runoff, and gaseous N. The current study established a field experiment to investigate the effects of drip irrigation and optimized fertilization on vegetable yield, water and fertilizer efficiencies and N<sub>2</sub>O emission in a typical intensive plastic-shed tomato production region of China. The treatments include CK (no fertilization, flood irrigation), FFP (farmers’ conventional fertilization, flood irrigation), OPT1 (80% of FFP fertilization, flood irrigation), OPT2 (80% of FFP fertilization, drip irrigation). N<sub>2</sub>O isotopocule deltas, including δ<sup>15</sup>N<sup>bulk</sup>, δ<sup>18</sup>O and SP (the <sup>15</sup>N site preference in N<sub>2</sub>O), have been used to investigate microbial pathways of N<sub>2</sub>O production under different treatments. Our results showed: i) optimized fertilization and drip irrigation significantly improved the fertilizer and water use efficiency without reducing tomato yield, ii) compared with flood irrigation, drip irrigation decreased soil WFPS and soil ammonium content, but increased soil nitrate content. When soil moisture was higher than 60%WFPS, drip irrigation led to a decrease of N<sub>2</sub>O emission with lower N<sub>2</sub>O SP signature observed than that of food irrigation, suggesting a reduction of denitrification derived N<sub>2</sub>O. In contrast, drip irrigation significantly increased N<sub>2</sub>O emission and N<sub>2</sub>O SP value when soil moisture status was lower than 55% WFPS, which may be due to the enhanced nitrification or fungal denitrification derived N<sub>2</sub>O.</p>

The substitution of polyethylene (PE) mulch for plastic biodegradable mulches (BDMs) in fruit and vegetable production has the potential to reduce the negative environmental impacts associated with PE mulch use, and the overall sustainability of fruit and vegetable production. A better understanding of the factors associated with BDM use could inform efforts to promote the use of BDMs. The main goal of this study is to assess the correlation between the use of BDMs among fruit and vegetable farmers, and labor savings and environmental stewardship. Using data from a Tennessee fruit and vegetable farmer survey and probit regressions, this study evaluates the correlation between the use of BDMs, and the labor savings associated with the use of BDMs and farmer environmental stewardship, after controlling for farmer and farmer business characteristics. Results suggest that farm size, farmer environmental stewardship, and labor savings from BDM use are strongly correlated with the use of BDMs among Tennessee fruit and vegetable growers, specifically among those farmers who are more likely to have previous experience using PE mulch.

COMPARISON OF ORGANIC AND INORGANIC MULCHES FOR HEIRLOOM TOMATO PRODUCTION

Cover crop impacts on soil organic matter dynamics and its quantification using UAV and proximal sensing

Microbial properties of rhizosphere soils as affected by rotation, grafting, and soil sterilization in intensive vegetable production systems

Cover cropping affects soil N 2O and CO 2 emissions differently depending on type of irrigation

Vegetable and fruit consumption patterns in the United States indicate that most people need to eat far more fruits and vegetables to meet the current nutritional guidelines for a healthy diet. Following these guidelines would require more than doubling the harvested acreage for fruits and vegetables and could have serious environmental implications if unsustainable production practices were used. This situation will likely intensify with population growth and climate change. To answer the title question (can we grow organic or conventional vegetables sustainably without cover crops?), this paper focuses on the high-input, tillage-intensive vegetable production practices in the Salinas Valley of California, a region often called “the Salad Bowl of America.” This region has a serious problem of nitrate contamination of the groundwater that occurred as the agricultural systems here shifted from agronomic to high-value horticultural crops [primarily vegetables and strawberries ( Fragaria × ananassa )] over the past several decades. This raises questions about the sustainability of past and current vegetable production practices and indicates the need for a radical paradigm shift in nutrient management. Cover cropping is well recognized as a “best management practice” in vegetable production systems, but is still relatively uncommon in many of the most important vegetable production regions in the United States, including the Salinas Valley. It is argued that cover crops are an essential part of sustainable vegetable production because they provide a complex suite of unique ecosystem services during fallow periods that complement best management practices during cash crop periods. The reasons that cover crops are uncommon here are discussed and three alternative cover cropping strategies are described to potentially increase adoption of cover cropping in vegetable rotations. These strategies are focused on reducing residue management challenges and include a novel strategy to extract the juice from nitrogen-rich, immature cover crops for use as a liquid organic fertilizer in subsequent cash crops.

The impact of land consolidation on arable land productivity: A differentiated view of soil and vegetation productivity

Sandy loam, characterized by inherently poor water retention capacity, necessitates the strategic utilization of fallow periods for soil conservation, with cover cropping serving as an effective ecological measure for nutrient retention. This study was conducted in the northern foothills of the Yinshan Mountains in Inner Mongolia, China, where the soil type is predominantly sandy loam. This study was conducted to elucidate the dynamic impacts of cover crops on soil nutrient profiles and their subsequent effects on following cash crops. Cover crops were cultivated during the fallow period and incorporated into the soil prior to spring tillage before planting the subsequent potato crop. Throughout the year following cover crop sowing, monthly measurements of soil organic matter (SOM) and nitrate nitrogen (NO3−-N) were performed to track temporal nutrient fluctuations. Concurrently, the biomass and yield of the subsequent potato crop were monitored to evaluate agronomic outcomes. The results indicate that the winter wheat treatment (WW) increased SOM by 2.54% after one year and elevated NO3−-N levels by 110.17% prior to potato planting. Subsequent potato cultivation exhibited yield enhancements of 2.51–3.83 t ha−1 relative to non-cover crop systems. Notably, 20% nitrogen reduction in basal fertilization did not compromise tuber yields while significantly improving nitrogen use efficiency by 8.7–12.3 percentage points and partial factor productivity of nitrogen by 14.6–18.9 kg kg−1, indicating optimized nitrogen stewardship under cover crop-mediated soil improvement regimes.

BackgroundRehabilitation and optimized utilization of agro-pastoral dams (APDs), especially for vegetable production, has been recently promoted to boost agricultural production and ensure food security in Benin. However, little information was available on APDs’ agricultural potentials and knowledge of how APDs’ ecosystem services were exploited by the various stakeholders, and how each stakeholder group contributed to the degradation of the common good was scanty. This study explored three APDs in northern Benin to diagnose vegetable production systems and assess producer’s perception of APD degradation.ResultsThe results indicated that vegetable production around the APDs was a part-time activity dominated by women, and characterized by low external input use and a diversity of African indigenous vegetables. There was a strong gender difference in cropping systems, farming practices and land access, and a significant agreement on key production bottlenecks among producers. The main constraints included conflicts with livestock herders generated by the recurrent destruction of crops and seedlings by livestock, lack of equipment, pest and disease management challenges, access to water and inputs. Water erosion and runoff, livestock, vegetable production and food crops and cotton farming around the dams were respectively perceived as factors that contribute to APDs’ siltation and affect water quality. In comparison with water erosion and runoff, experienced producers and those with higher vegetable species richness were more likely to rank farming as first source of threat to APDs. Urbanization and market access were drivers of intensification of vegetable production around APDs.ConclusionsOur findings illustrate how information on cropping and farming practices, and producers’ perception can provide insights and research and development avenues for integrated dam management and sustainable production for improved food security and livelihoods. We discussed the implications of our findings and suggested a number of strategic decisions and research avenues for integrated dam management and sustainable vegetable production around APDs. Avenues for future research and development actions include: (1) a tailored and gender-specific training programme on sustainable production practices targeted to women; (2) developing scenarios of the desired future state for APDs by all stakeholders to work towards through collaborative actions; and (3) assessing the perception of other users on APD siltation and water quality.

Irrigation and fertilization are critical aspects in oil palm nurseries, so they need to be appropriately managed. Automatic drip irrigation technology has the advantage of saving water and labour usage. On the other hand, correctly applying slow-release fertilizer can fulfil the need for oil palm seedlings. The combination of drip irrigation and the application of slow-release NPK fertilizer can increase the effectiveness of maintaining oil palm seedlings. This study aims to obtain the best watering time and rate of slow-release NPK fertilizer on the growth and performance of oil palm seedlings in the main nursery. A field study was conducted since June 2021 until August 2021 at the Oil Palm Nursery Unit in Politeknik Negeri Lampung, Indonesia. The experiment arranges in split-plot design in randomized block design with three replications. The watering time is the main plot, and the slow-release NPK fertilizer rate is the subplot. The results showed that application of drip irrigation system with watering time in the morning, midday, and afternoon significantly affect stem diameter and number of leaves at three months after observation. The rate of 20 g plant-1 slow-release NPK fertilizer best-affected plant height, stem diameter, number of leaves, leaf area, and greenness index.

As the name implies, a cover crop consists of plants grown primarily to keep the land covered, especially during the off-season or between cash crops. In temperate regions like most of Europe and North America, a cover crop sown immediately after the main crop harvest in fall is considered a winter cover crop. It will grow in the fall, either subjected to frostkill or go into relative dormancy during the dead of winter, and then, if winter-hardy, recommence growth in very early spring before soils are warm and dry enough for the next cash crop. If the climate is sufficiently mild, such cover crops may produce substantial above-ground dry matter (3000–6000 kg ha−1) and nearly complete ground cover before being terminated. For many decades, the use of cover crops has been promoted mainly to prevent the severe soil erosion that winter and spring rains can bring if soils are left bare. In addition, it is widely recognized that regular use of winter cover crops – as compared to bare fallow over winter – can provide enough carbon input to build – or at least slow the decline of – soil organic matter. For these reasons, many scientists view cover crops as an essential tool in managing farmland for long-term sustainability.1 A considerable amount of cover crop research has been conducted in the mid-Atlantic region of the USA during the past three decades. Most of this research focused on just a handful of cover crop species, mainly cereal rye and hairy vetch, which were found to be well adapted to the region’s climate and cropping systems. With the advent of programs to restore the health of the Chesapeake Bay, most cover crop research in Maryland has been directed towards using cover crops to capture residual mineral nitrogen (N) before it can leach away in the fall. Extensive research on coastal plain soils has demonstrated the ability of a rye cover crop to greatly reduce the loss of N to groundwater from maize grown in no-till production systems.2 However, relatively little has been done to demonstrate direct benefits to the farmer from the use of cover crops. One economic benefit that has been well quantified is the ability of legume cover crops, under some conditions, to replace by biological N2 fixation most or all of the fertilizer N needed for optimal production of nitrogen-demanding crops. However, under realistic conditions, research indicates that it costs about as much to grow and manage a hairy vetch cover crop as the value of the N fertilizer it saves.3,4 While biologically fixed N is likely to become more profitable as the cost of N fertilizer rises, legume cover crops grown alone are not very effective at capturing residual fall N. Although not often discussed by researchers, farmers recognize that growing a cover crop adds extra expense, complexity and uncertainty to the already risky business of farming. Under some circumstances, certain cover crops have interfered with crop production by using up water stored in the soil profile, by immobilizing N needed for the cash crop and by becoming weedy or producing excessive residues, hampering crop stand establishment or harvest. The most obvious direct costs associated with cover crops include those for cover crop seed, labor, fuel, fertilizer and herbicide or tillage to kill the cover crop. Given these considerations, the State of Maryland has for several years paid subsidies of $50–100 per hectare for timely planting of cover crops with a goal of keeping at least 75% of Maryland’s cropland acres under cover crops in winter. Despite this incentive, adoption rates remain relatively low, with only about 20–25% of cropland hectares receiving cover crops. We suspect that this is because most farmers in this region are not sufficiently aware of the direct benefits that cover crops potentially offer, possibly as a result of past research and extension work that emphasized cover cropping’s role in N fixation, environmental protection and long-term soil resource conservation. Although nearly all farmers desire to be good stewards of their land, most face tight (or negative) profit margins and cannot afford to engage in environmental altruism without first considering their operations’ bottom line and efficiency goals. Lacking credible information and examples that might convince them otherwise, many farmers have reached the conclusion that cover crops are simply not worth the cost and trouble.

China's vegetable production has experienced a rapid growth in recent years. Total production amounted to 522.7 million Mg (1 Mg = 10 g) in 2009, which was more than nine times that in 1980 and represented >50% of the world production. Meanwhile, excessive use of animal manures and chemical fertilizers in vegetable fields has brought various production and environmental challenges, including excessive accumulation of nutrients in soils and accelerated water pollution problems. In this study, we have evaluated the current status of phosphorus (P) in China's intensive vegetable production systems based on data summarized from nearly 100 publications plus results from our recent experiments. Gross overfertilization occurred in greenhouse (571 kg P ha) and open-field (117 kg P ha) vegetable systems compared with P removal in harvested crops (44 and 25 kg P ha) per season. Excess P input led to soil enrichment of labile P, measured as Olsen-P, averaging 179 (greenhouses) and 100 mg P kg (open fields) in the 0- to 20-cm soil depth, and in some cases led to P leaching, as evidenced by increases in Olsen-P and CaCl-P at the 40- to 60-cm soil depth. The vast majority of vegetable soils had Olsen-P exceeding the critical level (46.0-58.0 mg P kg) for optimum vegetable yield. Innovative policies and strategies are urgently needed to implement science-based nutrient management practices to attain sustainable vegetable production while protecting natural and environmental resources.

Influences of drip and flood irrigation on soil carbon dioxide emission and soil carbon sequestration of maize cropland in the North China Plain