Vegetable Production Systems Research Articles

How much is too much? Quantifying pesticide overuse in vegetable production in Southeast Asia

This paper quantifies the extent of pesticide overuse in vegetable production systems in Southeast Asia. Pesticide overuse was defined as levels of use in excess of an economic (profit-maximizing) optimum. A production function with an exponential damage abatement term was estimated. Data come from a representative sample of 1000 farmers producing leaf mustard and yard-long bean in Cambodia, Laos and Vietnam. The results show that 100% of the sampled farmers in Vietnam, 73% in Cambodia and 59% in Laos overused pesticides. Pesticide expenditure in excess of the economic optimum was 96% for Vietnam, 92% for Cambodia, and 42% for Laos. Pesticide overuse was positively associated with men in charge of pest management decisions, farmers seeking advice from pesticide sellers and a strong belief that pesticides are effective. It was negatively associated with the use of non-chemical methods of pest control. These results imply that farmers in Southeast Asia are spraying excessively and inefficiently and could increase their profits by applying fewer pesticides.

Quantifying trade-offs among on-farm and off-farm fertility sources to make vegetable organic farming systems more sustainable

A core principle of organic farming is the reliance on internal nutrient recycling, favoring nutrient sources produced on farms (e.g.,manures) as opposed to those that are not (e.g., processed fertilizers, municipal compost). Soil fertility management varies tremendously among organic vegetable production systems, potentially with large effects on crop productivity, the environment, and trade-offs between them. We compared four certified organic systems using manure, municipal waste compost, and/or processed fertilizers to grow a mix of vegetable crops with variable nutrient demand. The four systems added nutrients to meet recommended nitrogen (N) inputs, estimated phosphorus (P) removal, or both, with different trade-offs expected between crop yields and environmental impacts depending on the imbalance in N:P ratio between fertility sources and crop removal. Municipal compost minimized trade-offs between yields and environmental impacts for crops with a low N demand (e.g.,beet). In these systems, we observed higher carbon inputs (2–6 fold), and lower residual soil N (40–50%) and nitrous oxide (N2O) emissions (50–75%) compared to systems based on manures or processed fertilizers. In contrast, the manure-based system had the highest crop yields when N demand was high (e.g., cauliflower), but also the highest environmental impacts. Using processed fertilizers instead of manure typically lowered N2O emissions (45%) and P surpluses (85%), but it also reduced yields (10%). Overall, our results confirm the need to develop high-yielding organic vegetable systems that minimize environmental impacts and the challenge of minimizing farm-scale yield-environment trade-offs without relying on off-farm fertility sources.

Energy use pattern and greenhouse gas emission in systems for greenhouse vegetable production

Abstract. Algeria has experienced a notable agricultural development driven by a prosperity in market gardening in plastic greenhouses due of the favorable climatic conditions and the government’s policy. For that, a survey has been conducted in order to determine the energy use pattern for greenhouse vegetable production, also to estimate the greenhouse gas (GHG) emission for this system of production in Biskra province, Algeria. The results revealed that the total energy required for vegetable protected production is 119.68 GJ per hectare where the infrastructure was the highest energy consumer followed by the electricity and fertilizers with a share of 22%, 20% and 19%, respectively. The energy use efficiency (energy ratio) was calculated as 0.82, showing the inefficiency use of energy in the protected vegetable production. The inputs of farmyard manure, followed by infrastructure and electricity in greenhouse vegetable production generated the highest proportion of gas emissions with values 35%, 33% and 23%, respectively. According to these results, management of electricity and diesel fuel consumption are possible using solar energy to decrease total GHG emission in greenhouse vegetable production in Biskra province.

Life cycle assessment of potential pollutant-induced human capital loss caused by different agricultural production systems in Beijing, China

Abstract Concerns about human health problems associated with adverse environmental impacts have been raised worldwide, and the direct quantitative relationship between pollutants and economic cost is often highlighted. However, few studies have focused on the agricultural sector, and the relationship between human health impact and agricultural production processes remains poorly understood. This study aims to fill this gap by identifying the quantitative relationships among agricultural production systems, pollutants, and human capital losses (HCL) using a dose−response model that combined with life cycle assessment and the amended human capital method. We analyzed maize, vegetable, and peach production systems in the Beijing metropolitan region (BJMR). The results showed that the HCL was closely related to the amount and types of external inputs in different intensive agricultural systems. Through the dose−response model, all of the three production systems performed significantly negative externalities, among them, the vegetable production system was identified as a pattern with both greatest economic outcomes and highest HCL, to expand vegetable cultivated area has a potential risk of increasing HCL. As to external inputs, fertilizers contributed most to the HCL, followed by electricity and other inputs. In addition, a cost−benefit analysis indicated that the vegetable production system had the highest level of eco-efficiency from the perspective of HCL and net benefit per unit area, that means converting vegetable into maize production in the BJMR would substantially reduce less HCL with more economic losses. Therefore, our results suggest that consideration should be given to balance the HCL and economic outcomes when developing policies aimed at promoting environmentally friendly agricultural practices in the BJMR, and in other regions worldwide.

Sustainability assessment of crop production in accord with energy, environment and economic performances in Nepal

Increasing crop production usually warrants increased use of energy in the system that triggers the question of locating an ‘appropriate’ operating point by weighing the economics of output and its environmental impacts. Sustainability of diverse cereals, legumes and vegetable production systems were assessed in lowlands of Nepal in light of the efficiency of energy use, CO2e (carbon dioxide equivalent) emissions and financial return–cost ratios. The energy saving potential of 238 farms selected in the study area is calculated adopting Data Envelopment Analysis (DEA). Based on the per-hectare energy consumption, vegetables (12.37 GJ), cereals (10.60 GJ) and legumes (3.80 GJ) crop production systems are ranked in descending order. Rice offered the highest per-hectare energy output (68.99 GJ) among the selected crops. Potential saving of energy inputs in the study area is shown to be between 18 and 35% without conceding yield of the particular crop production system. The highest environmental impact is due to garlic production (2997.13 kg CO2e ha−1); while rice, maize, wheat, lentil, mungbean and onion crops emit 60, 63, 28, 5, 3 and 86% CO2e emissions (of that of garlic crop), respectively. As expected, the vegetable production remains the most profitable system with the return–cost ratio of 2.96–3.52, followed by legume (1.83–2.16) and cereal (1.21–1.96) production systems.

Nitrogen pollution and sources in an aquatic system at an agricultural coastal area of Eastern China based on a dual-isotope approach.

Nitrogen (N) pollution of water courses is a major concern in most coastal watersheds in eastern China with intensive agricultural production. We use hydrogeological and dual-isotopic approaches to analyze the N concentrations, pollution, transformations, and sources of surface water and groundwater in an agricultural watershed of the Jiaozhou Bay (JZB) area. Results showed that dissolved total N (DTN) concentrations in sub-rivers (SRs) ranged from 6.0 to 25.3mg NL-1 in the dry season and 9.1-26.7mg NL-1 in the wet season, which indicated a positive relationship with the percentages of agricultural land. Meanwhile, the dominant dissolved N species in SRs changed from nitrate (NO3-, 64-100%) to dissolved organic N (DON, 52-77%) from the dry season to the wet season and the increased DON concentrations showed a positive relationship with the planted proportions of vegetable production systems. The NO3- concentrations of groundwaters ranged from 10.6 to 121.4mg NL-1, which were over the limit for drinking water by the World Health Organization. Isotopic analysis indicated that most NO3- originated from the microbiological conversion via nitrification, whereas the deletion of denitrification was insignificant in this area. The results of the stable isotope analysis in R mixing model showed the contributions of potential NO3- sources which were in order of manure fertilizers (20.6-69.0%) > soil organic matter (19.5-53.2%) > chemical fertilizers (5.5-34.3%) > atmospheric deposition (1.3-18.8%). This study suggests that the management of crop productions and reasonable manure fertilizer application should be implemented to protect the quality of aquatic systems in the JZB area.

Effect of full substituting compound fertilizer with different organic manure on reactive nitrogen losses and crop productivity in intensive vegetable production system of China

How substituting compound fertilizer with organic manure affects crop productivity and reactive nitrogen (Nr) losses from vegetable production system during the cradle-to-gate life cycle is not well understood. We thus investigated the impact of substituting compound fertilizer with various organic manures (stored solid manure and composted manure) on spinach productivity, Nr losses (e.g. NH3, N2O, NOx, N-leaching) and yield-based Nr losses in Changsha, Hunan, China. We found that the application of stored solid manure and composted manure decreased the total Nr losses by 58.1% and 75.0%, respectively, compared with compound fertilizer, but the spinach productivity was also decreased by 27.9% and 16.4%. Overall, substituting compound fertilizer with organic manure decreased yield-based Nr loss by 41.9–70.1%. These results highlight that substituting compound fertilizer with organic manure, particularly composted manure, may be beneficial to the environment at the expense of vegetable productivity. Strategies should be developed to decrease Nr losses from N input without compromising productivity in intensive vegetable production system.

Source tracking of Shiga-like toxin-producing Escherichia coli in the fresh vegetable production system of South India

Numerous outbreaks of foodborne diseases through fresh agricultural produce urge research to assess the source of entry of pathogens to the produce that compromise microbiological safety. In the present investigation, the entry of shiga-like toxin-producing Escherichia coli O157:H7 in a fresh vegetable production system was assessed by microbiological and molecular approaches. Five major vegetables, viz., beetroot, cabbage, carrot, onion, parsley, and potato, being cultivated routinely in the Western Guats of South India (The Nilgiris), were assessed for the prevalence of E. coli O157:H7. The fresh produce, rhizosphere soil, and water resources were sampled and the total coliforms and E. coli counts were assessed by plate count method and the O157:H7 by polymerase chain reaction targeting shiga-like toxin gene (stx1). The results revealed that all the vegetables collected from the fields had high levels of total coliforms (3 log CFU per g) with high proportions of E. coli (1–2 log CFU per g). The prevalence of O157:H7 among the E. coli isolates in these vegetables ranged from 0 to 5.8%. However, the prevalence of O157:H7 in rhizosphere soil of these vegetables was relatively high (1.6 to 42.5%). The water used for irrigation and washing the produce (carrot) also showed the presence of O157:H7. The real-time quantitative PCR (qPCR)–based detection of stx1 revealed that the O157:H7 prevalence in these vegetables and their rhizosphere soil were in higher magnitude than the counts by culturable method. The rhizosphere soil and water samples had higher O157:H7 CFU equivalents than fresh produce. It is evident that the soil as well as the irrigation and process water got contaminated with feces, which are assumed to be the primary source and cause for the entry of O157:H7 to the fresh vegetable. Hence, good agronomical practices and good hygiene post-harvest practices have to be imposed in the vegetable production system to avoid the pathogen entry.

Nitrogen loss and greenhouse gas flux across an intensification gradient in diversified vegetable rotations

Vegetable production area is growing rapidly world-wide, yet information on nitrogen (N) losses, greenhouse gas emissions, and input efficiency is lacking. Sustainable intensification of these systems requires improved understanding of how to optimize nutrient and water inputs for improved yields while minimizing N losses. In this study, a 3-year vegetable crop rotation spanning an intensification gradient is investigated in Kentucky, USA: (1) a low input organic (LI), (2) high tunnel organic (HT), and (3) conventional (CONV) system. The objectives were to (1) characterize soil mineral N pools and NO3−–N leaching, (2) quantify CO2 and N2O fluxes, and (3) relate crop yield to global warming potential (GWP) caused by CO2 and N2O losses in these three vegetable production systems. HT maintained consistently higher soil NO3−–N; the average NO3−–N content during the entire rotations in HT was twice as high as in the CONV and three times as high as in the LI system. Key N loss pathways varied between the systems; marked N2O and CO2 losses were observed in the LI and NO3− leaching was greatest in the CONV system. The 3-year cumulative CO2 emission in LI was 50% higher than in the CONV and HT systems. Cumulative N2O emission over the 3-year vegetable rotations from the LI was twice as high as in the CONV system, whereas 60% more N2O was produced from the HT than from the CONV system. Yield-scaled GWP was greater in the LI for all crops compared to HT and CONV systems.

Performance of Permanent Vegetable Production Systems Designed with the PermVeg Model for the Red River Delta, Vietnam

The aim of the research described was to design permanent vegetable production systems for the Red River Delta in Vietnam. Permanent vegetable production systems better meet the increasing consumer demand for vegetables and may increase farmers’ income. Optimum crop sequences for permanent vegetable production in the Red River Delta were designed with the recently developed model PermVeg. The crop sequences designed were tested in a field experiment from May 2007 to May 2009. The production systems tested were five systems designed according to the scenarios of (i) high profitability, (ii) low labor requirement, (iii) low costs of pesticide use, (iv) high level of crop biodiversity, and (v) low perishable products, respectively. The five systems were compared with the traditional vegetable production system. At local prices, only the high profitability and low labor requirement systems yielded significantly higher profits than the traditional system. At city wholesale market prices, profits of all permanent vegetable production systems were significantly higher than that of the traditional system, except for the low perishability system. Permanent vegetable production systems required more labor than the traditional system. Labor-day incomes of permanent vegetable production systems generally were not higher than those of the traditional system. The labor-day income increased only with the low labor requirement system at city wholesale market prices. The model outcomes correlated reasonably well with the labor requirement and the length in days of production systems in the field. The model poorly predicted profits and costs of pesticide use. We concluded that permanent vegetable production systems can yield higher profits than the traditional system, and can contribute to enhancing employment opportunities and increasing household income.

Anaerobic Soil Disinfestation to Manage Soilborne Diseases in Muck Soil Vegetable Production Systems.

Anaerobic soil disinfestation (ASD) was evaluated as a tool for managing the root-knot nematode Meloidogyne hapla in lettuce (Lactuca sativa) and clubroot disease, caused by Plasmodiophora brassicae, in mustard greens (Brassica juncea) produced on Ohio muck soils in Huron and Stark Counties. In two consecutive years of field trials, wheat bran (20.2 Mg ha-1), molasses (10.1 Mg ha-1), and wheat bran (20.2 Mg ha-1) plus molasses (10.1 Mg ha-1) were assessed as ASD carbon sources and compared with nonamended controls. Data were collected from plants grown in the field and from plants grown in field-treated soils in growth chamber-based post-ASD bioassays. Anaerobic conditions developed in ASD-treated soils in both trial years, as indicated by polyvinyl chloride pipes painted with an iron oxide paint. Soil pH did not decrease during ASD at the Huron County site of the mustard greens clubroot trials in either trial year but soil pH decreased significantly during ASD in Stark County soils treated with ASD with either wheat bran or wheat bran plus molasses compared with control soils in both trial years. Impacts of ASD on plant biomass were inconsistent in direct field measurements; however, significantly higher biomasses were observed in lettuce and mustard greens grown in bioassay soils collected from plots treated with ASD with wheat bran-based amendments compared with plants grown in soils from control plots. Based on direct field measurements and bioassays, the use of ASD with any carbon source led to significant reductions in root-knot nematode galling on lettuce compared with controls. Reductions in clubroot severity in mustard greens following ASD were less consistent; however, significant reductions in clubroot severity were observed in the field in one trial year and in both years of bioassays. The results of these studies indicate that ASD is a promising tool for managing soilborne diseases in muck soil vegetable production systems.

Evaluating sorghums as green manure against root-knot nematodes

Current restrictions on the use of chemical nematicides have led to an increase in root-knot nematode (RKN) damages in horticultural crops. The effects of two sorghums as summer cover crops, Sorghum sudanense sudangrass cv. ‘Piper’ or sudangrass hybrid [S. bicolor x S. sudanense] ‘270911’, respectively with low and high dhurrin contents, were compared in their ability to suppress RKN in a vegetable production system. The use of both sorghums ‘Piper’ and ‘270911’ as a green manure was found to be an effective strategy for decreasing RKN infestation in the soil, thereby protecting the subsequent planting of RKN susceptible crops (chard, lettuce or melon). Analytical experiments were further conducted in growth chamber and greenhouse pot experiments to investigate and compare the susceptibility of the sorghums and the factors affecting their efficacy for RKN management, in order to better explain the results obtained in the field trial. The two sorghums were poor hosts of RKN, acted as trap crops and as a biofumigant releasing hydrogen cyanide. Time of planting, time of biofumigation, and type of soil affected their efficacy for RKN management. For best RKN suppression, the sorghum cover crops need to be cultivated during one month or less and biofumigated for one month prior to crop planting. The trapping effect of both sorghums in clayey soil was less efficient than in sandy or sandy-loamy soils. Combining less than 30-days of sorghum culture and 10-days soil incorporation with solarization mulch was particularly efficient in suppressing nematodes. No effect relative to the sorghum type was detectable as long as they were used appropriately.

Reduction in field emergence and seedbank density of Galinsoga quadriradiata and other weeds after contrasting false seedbed strategies in organic vegetable fields

SummaryMechanical weed control in low competitive, organic vegetable production systems is challenging, particularly in fields with large populations of Galinsoga spp. (Asteraceae). Various false seedbed techniques are used prior to crop planting or sowing to prevent weed emergence, albeit with variable success. This study investigated the impact of machinery type (flamer, hoe and harrow), number of passes (2 and 4), tillage depth (1–4 cm) and intensity (double and single hoeing, and hoeing with or without additional harrowing) on weed emergence and seedbank density in 0–5 cm topsoil of organic vegetable fields. False seedbed machinery that did not or minimally disturb the soil was most appropriate for preventive control of Galinsoga quadriradiata (Hairy galinsoga) and total weed seeds, with reductions in seedling emergence up to 99% and 73%, respectively, for flaming, and 74% and 67%, respectively, for 1 cm deep hoeing, 1 month after false seedbed creation. Compared with 1 cm deep hoeing, 1 cm deep harrowing was 16% less effective in the control of emerged seedlings, while flaming was highly effective in preventing weed seedling emergence, even after a low number of passes. Tillage intensity was less important than tillage depth for the reduction in weed emergence and seedbank density. Overall, tillage was more effective for seedbank reduction than flaming.

Partial substitution of chemical fertilizer with organic amendments affects soil organic carbon composition and stability in a greenhouse vegetable production system

Understanding soil organic carbon (SOC) composition and stability is necessary for long-term carbon (C) sequestration. Fertilization is known to modify SOC stability and composition; however, inconsistent results have been reported. Here, we evaluated the changes in SOC composition and stability through multiple methods in an 8-year fertilization experiment under greenhouse vegetable production (GVP) systems in Tianjin, China. This experiment was designed to supply an equivalent amount of nutrients (N, P2O5 and K2O) but variable amount of C through different exogenous organic resources (ORs) input. Five treatments were included based on substitution of chemical fertilizer nitrogen (N) with different exogenous ORs: no N (no nitrogen inputs), 4/4CN (CN, nitrogen in chemical fertilizer), 2/4CN + 2/4 MN (MN, nitrogen in pig manure, high-quality ORs), 2/4CN + 2/4SN (SN, nitrogen in corn straw, low-quality ORs) and 2/4CN + 1/4 MN+1/4SN. Organic fertilization strategies promoted SOC accumulation and reduced SOC stability by increasing labile C fractions, whereas chemical fertilizer alone had a negative effect on SOC accumulation by consuming labile C fractions but enhanced SOC stability. Notably, the characteristics of high temperature, nutrient availability and C inputs in organically managed soils in GVP systems weaken the influence of ORs quality on SOC stability. Consequently, high doses of C inputs (11.5 and 18.5 Mg ha–1 year–1 in 2/4CN + 1/4 MN+1/4SN and 2/4CN + 2/4SN treatments) induced lower SOC stability than low doses of C inputs (4.5 Mg ha–1 year–1 in the 2/4CN + 2/4 MN treatment), irrespective of ORs quality. In addition, strong correlations were found between SOC thermal characteristics and SOC chemical and 13C NMR spectral properties, indicating that thermal analysis techniques can characterize SOC stability effectively.

Heavy metal contamination in soils of greenhouse vegetable production systems in a cold region of China

Heavy metal (HM) contamination in soils of greenhouse vegetable production (GVP) systems has drawn increasing attention in terms of food safety. In the present study, 64 surface soils were sampled, and the concentrations of select HMs were determined using atomic absorption spectroscopy. The results showed that the concentrations of cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), nickel (Ni) and chromium (Cr) in the soils were (0.2±0.2) mg/kg, (26.5±8.4) mg/kg, (101.4±43.2) mg/kg, (29.1±8.6) mg/kg, (24.5±3.3) mg/kg, and (56.5±6.3) mg/kg, and the corresponding accumulation index (AI) values were 2.30, 1.10, 1.43, 1.45, 1.07, and 0.97, respectively. The spatial distribution of the HMs suggested that Cd pollution displays a fractionation effect, which may be related to the source of Cd and its mobility. The concentration of Zn was significantly correlated with that of other HMs, implying that a comprehensive interactive effect might occur between Zn and other HMs. Furthermore, the values of the potential ecological risk index (RI) ranged from 41.23 to 185.91, meaning that attention should be paid to HM contamination of GVP soils to ensure food quality and safety. Keywords: heavy metal contamination, cold region, greenhouse vegetable production (GVP), distribution, ecological risk, food quality, food safety DOI: 10.25165/j.ijabe.20191202.4306 Citation: Lv P, Wei Z M, Yu Z M, Zhang J Z, Wang L M. Heavy metal contamination in soils of greenhouse vegetable production systems in a cold region of China. Int J Agric & Biol Eng, 2019; 12(2): 98–102.

Profitability and constraints to urban exotic vegetable production systems in the Kumasi metropolis of Ghana: a recipe for job creation

Some vegetable producers perceive their venture to be unprofitable owing to cheating at the farm gate. This study sought to determine profitability of production of exotic vegetables which are not native of Ghana. The study used data collected from 80 urban exotic vegetable farmers. Descriptive statistics, gross margin analysis, multiple linear regression, and the Garrett ranking scale were the methods of analysis. The most profitable system from the results of the net margin ratio was the production of lettuce as a sole crop with net margin ratio of 71% which explains the popularity of lettuce among exotic vegetable producers in the metropolis. Household size, experience, and access to credit positively affected profitability while farm size as well as costs of labor and fertilizer had negative effects. Farmers ranked high input cost, land tenure insecurity, and high cost of irrigation as challenges to urban exotic vegetable production. We recommend that urban exotic vegetable production should be considered as a source of employment. Government and financial institutions should improve farmer access to credit to enable them to hire adequate labor and acquire technologies and production inputs.

Agro-biological and economic efficiency in a beetroot (Beta vulgaris L.) production system fertilized with hairy woodrose (Merremia aegyptia (L.) Urb.) as green manure

Beetroot (Beta vulgaris L.) is a tuberous vegetable that is under experimentation in the vegetable production system in Rio Grande do Norte state (Brazil). It is quite demanding, in nutritional terms. One of the alternatives to meet this need is green manuring using spontaneous species of the Caatinga biome. The aim of the present work was to optimize the agro-biological performance and economic profitability of the beetroot 'Early Wonder', fertilized with different doses of hairy woodrose (Merremia aegyptia (L.) Urb.) in this semi-arid environment. Hairy woodrose is a spontaneous species of the Caatinga biome that is widely distributed, being found in forests, fences, forest clearings and fields, growing in soils of different textures, producing biomass with a high content of macronutrients. This material was collected from spontaneous vegetation, native to the region, and used as green manure.The experimental design was a randomized complete block, with four treatments and five replicates. The treatments consisted of four amounts of hairy woodrose biomass incorporated into the soil (10, 25, 40 and 55 t ha-1 of dry matter). The following agronomic characteristics were evaluated in each beetroot treatment: plant height, fresh mass of shoots, number of leaves per plant, dry mass of shoots and dry mass of roots, total and commercial root productivity, and root productivity classified into scrap and extra roots, extra A roots, extra AA and great roots. Apart from these characteristics, the following economic indicators were also determined for each treatment: gross income, net income, rate of return and profit margin. The maximum agro-biological efficiency of beet root productivity (22.68 t ha-1) was obtained from 44.92 t ha-1 of hairy woodrose biomass added to the soil. The maximum economic efficiency of the yield of beet roots was achieved as a net income of AU$2,491.00 (R$6,406.36) ha-1, provided by the production of 22.04 t ha-1 of commercial roots, using 37.03 t ha-1 of hairy woodrose biomass incorporated into the soil. The use of hairy woodrose as green manure presents agro-economic feasibility in beet cultivation in this semi-arid environment.

Substituting organic manure for compound fertilizer increases yield and decreases NH3 and N2O emissions in an intensive vegetable production systems

Substituting organic manure for compound fertilizer may play an important role in regulating the nitrogen (N) cycle and consequently affecting crop yield in agroecosystems. However, how substituting different organic manures for compound fertilizer affects crop yield and ammonia (NH3) and nitrous oxide (N2O) emissions in the vegetable system during the life-cycle production (including storage and field application) remains poorly elucidated. Thus, we conducted a greenhouse experiment to investigate the effects of substituting organic manure species, i.e., stored swine manure fertilizer (SS), swine manure covered by straw (CS), stored swine fertilizer mixed with biochar (BS), and stored swine manure fertilizer with void expansion (OS) for compound fertilizer (FC) on rapeseed yield and NH3 and N2O emissions in a rapeseed-cropping system in China. The results showed that the total gaseous N losses (NH3 and N2O) were 1.6, 1.4 and 1.1 times higher in SS, CS and OS than FC, respectively. However, total gaseous N losses in BS was 0.9 times less than FC. Compared with FC, rapeseed yield and N uptake in SS and CS were decreased by 17.2–20.2% and 16.0%–28.1%, respectively, but which were increased by 7.3% and 54.1% in BS, respectively. In addition, OS decreased rapeseed yield by 17.2%, but increased N uptake by 8.5%. Therefore, the effects of substituting organic manure for compound fertilizer on rapeseed yield, N uptake, NH3 and N2O varied regarding different organic manure species. Adopting stored swine fertilizer mixed with biochar might be a sound management practice to reduce gaseous N losses and enhance N uptake and yield in intensive vegetable production systems.

English

The system of vegetable crops production required large amounts of mineral fertilizers. One of the possible alternatives to assure the economic and environmental sustainability of this production system would be the use of promoting growth plant rhizobacteria (PGPR). However, care is needed to select a microorganism to be used in crops that are usually consumed raw, so human health is not at risk. It was important to search for PGPR, as rhizobium, that already were broadly used as inoculants for leguminous plants for several decades, without risks to human health. PGPR can promote growth and development of plants through direct and indirect mechanisms, by production and secretion of chemical substances in the rhizosphere. The direct mechanisms were involved with the uptake of nutrients by the plants (nitrogen, phosphorus and essential minerals) through phosphate solubilization, production of siderophores and growth regulators. The indirect mechanisms were involved with the decrease of inhibitory effects from various pathogenic agents related with biological pest control, thereby favoring plant growth. Nevertheless, due to its ability to promote beneficial effects to plants, effective bacterial colonization was extremely important. Some bacteria that colonized the rhizoplane may penetrate the plant roots and some strains may move to the aerial part, with decreased bacterial density, compared with colonizing populations in the rhizosphere or roots. It can be concluded that Rhizobia promotes plant growth using different mechanisms as biological nitrogen fixation and production of different plant growth regulators (e.g. auxins). Therefore, new studies with Rhizobia characterization and observation about its different mechanisms of promoting plant growth should be performed. Such information would be useful for the identification of plants with potential to increase agricultural production due to the benefits of using plant growth promoter’s rhizobia. Key words: Growth promotion, vegetable crops, rhizobacteria, growth regulators.

Life cycle analysis of monocrop and multicrop in conventional and organic vegetable production systems in Tayabas, Quezon, Philippines

Attaining food security is directly linked to increasing agricultural production to meet the needs of the exponentially increasing population. Extensive efforts in the past to improve crop production resulted to massive land conversion, deforestation and inappropriate use of modern technologies among others. Comparative assessment of the potential impacts of conventional and organic vegetable production systems is valuable because agriculture is one of the major contributors to environmental degradation. This study assessed and compared the environmental burdens of conventional and organic vegetable production systems in both monocrop and multi-cropping using the environmental Life Cycle Analysis (LCA) approach. The data gathered from in-depth interviews with farmers and farm surveys in Tayabas, Quezon, were used to determine the cropping system that has significant potential contributions to Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP) and Human Toxicity Potential (HTP) with land area and kg−1 of vegetable as functional units. The conventional vegetable multi-cropping system contributed 4.10E-02 kg CO2-eq kg−1 to GWP higher than the monocrop with only 3.69E-02 kg CO2-eq kg-1 potential contribution. Organic multicrop contributed less to GWP with only 2.48E-02 kg CO2-eq kg−1. AP of conventional multicrop is also higher with 6.79E-03 g SO2 -eq kg−1 as compared to the combined AP of organic monocrop and multicrop. Further, conventional vegetable production contributed higher HTP with 6.22E+06 g 1,4 DCB -eq kg−1 than organic. This study shows that organic production system has lower environmental burdens and a better alternative to improve food crop production while protecting the environment.