Protected Cultivation Of Vegetables Research Articles

Effects of strong reductive process on transformation of heavy metals in protected vegetable soil

The application of sewage and manure in protected vegetable cultivation can induce the occurrence of heavy metals contamination. The present research studied the transformation of heavy metals (Cd, Cu, Pb and Zn) by incubating contaminated protected soil with maize straw and then leaching. The results showed that soil pH was significantly decreased, being more evident in maize straw treatment; soil Eh dropped quickly below -280 mV. Maize straw treatment promoted the activation of Cd, Cu, Pb and Zn from soil, and the total percent of oxidizable fraction and residual fraction of Cd, Cu, Pb and Zn declined at 9th day; the amount of Cd, Cu, Pb and Zn in soil reduced 18.1%, 19.0%, 16.1% and 15.7% at 15th day, respectively. Compared to control, maize straw treatment could increase the concentrations of dissolved Cd and Zn, but Cu decreased. The concentration of colloidal-bound Cd and Pb increased, Cu decreased and no significant change occurred in Zn in maize straw treatment. Strong reductive approach could activate heavy metals in protected vegetable soil, increase the risk of heavy metals accumulation in vegetables, and possibly cause water pollution accompanied with soil water mobilization.

Sustainable vegetable production through the use of low-cost protective structures: a farmer’s experience in Bontoc, southern Leyte, Philippines

For years, Lucio Boie' R. Gerona, a civil engineer by profession but with a passion for business and farming by family orientation, had been dreaming of becoming a progressive farmer. Countless attempts in farming on his self-acquired land in Pamahawan, Bontoc, southern Leyte, Philippines, were made but often failed and/or were non-profitable. Among the many constraints, he found continuous heavy rains the most difficult and almost impossible to manage. With the use of protective structures (curved-roof and vent types with plastic roofing and bamboo framings) as rain shelters, year-round production of vegetables was made possible. Results showed that yields of lettuce (Lactuca sativa L.), ampalaya (Momordica charantia L.), and two croppings of sweet pepper (Capsicum annuum L.) were consistently higher with gross margins of nearly three fold as compared with those in the open field. Yields of two croppings of watermelon (Citrullus lanatus Thunb.), which were planted during the dry months, were also high although statistically comparable with those in the open field, which was understandable since watermelon is a sun-loving crop. With the adoption of the technology, Boie attained rewarding outcomes: sustained productivity and profitability which enabled him to put up other farm improvements (irrigation system, enclosed structures for leafy vegetables, vermiculture shed and mini-piggery to start diversification); capacity building that allowed him to serve as a consultant/resource speaker/panelist in farmer's fora/FFDs/training sessions specifically on protected vegetable cultivation and marketing; and not to mention the enhanced publicity of his farm, which is now a favorite educational trip destination for many people from all walks of life.

Production and Marketing of Vegetables as a Part of Integrated Farming: A Case Study of Entrepreneurial Efficiency

The present study pertains to a small but innovative farmer, having a land-holding of just 2.5 ha, who adopted integrated farming including protected cultivation of vegetables in three net houses covering an area of 1500 m2, open cultivation of cash crops in one hectare, processing of tomatoes, turmeric, mushroom (dhingri) cultivation, livestock, vermi-composting, and growing of general crops, like basmati, wheat and fodder in one hectare. Budgeting Technique and other statistical tools have been applied to work out the economics of his adopted separate enterprises as well as the entire integrated system as a whole. For the purpose of marketing and disposal of his produce, the vehicle, being used to sell small packets of well graded fresh vegetables to well defined clientele at some fixed destinations within the district on a particular time during the days of weeks, has also been purchased after having availed the subsidy of the due kind from the National Horticultural Mission. He is earning a net income in the tune of more than 8 lakh per annum. The economics of his farm speaks volume of his entrepreneurial ability and the hidden strength of new technologies and farm integration.

Tomato and cowpea crop evapotranspiration in an unheated greenhouse

With the development of protected cultivation of vegetables in China, it is necessary to study the water requirements of crops in greenhouses. Lysimeter experiments were carried out to investigate tomato (2001) and cowpea (2004) crop evapotranspiration (ETc) in an unheated greenhouse in Eastern China. Results showed remarkably reduced crop evapotranspiration inside the greenhouse as compared with that outside. ETc increased with the growth of the crops, and varied in accordance with the temperature inside the greenhouse and 20-cm pan evaporation outside, reaching its maximum value at the stage when plants' growth was most active. Differences between the variation of crop evapotranspiration and pan evaporation inside the greenhouse were caused by shading of the pan in the later period when the crops were taller than the location where the pan was installed, 70 cm above ground. The ratio of crop evapotranspiration to pan evaporation was not constant as reported in previous studies, and the variation of the inside ratio αin lagged behind that of the outside ratio αout. Simulation of crop evapotranspiration based on 20-cm pan evaporation inside the greenhouse is more reasonable than that based on 20-cm pan evaporation outside, although pan evaporation outside is more consistent with ETc than that inside. The value of αin, calculated based on air temperature, relative humidity, and ground temperature inside, plays a dominant role in the calculation of ETc. As the crop height increases, altering the location of the inside pan and placing it above the canopy, out of the shade, would help to achieve more reasonable values of crop evapotranspiration.

Protected Vegetable Cultivation Technology for Cold Arid Agro-ecosystem of Ladakh

Ladakh region is a high altitude cold arid desert with special agro-climatic features. The region is one of the driest and coldest inhabited places on the earth. Due to harsh climatic features, short growing season is unable to offer sufficient food particularly vegetables. To supplement, fresh vegetables have to be imported by truck in summer or flown in by air during winter. The unavailability and high cost means that local people rarely eat fresh vegetables during the winter spell of the year, but instead rely on dried leafy vegetables and only stored root crops and cabbages. Specialized agricultural practices need to be developed and demonstrated for food and nutritional security of the inhabitants of the region. Protected cultivation is a well defined sustainable technology for off season food production and thereby an important component in attaining nutritional security. It offers scope for the cultivation of plants under adverse conditions. Various naturally ventilated zero energy polyhouses have been tried and tested for the region. Despite the sub-zero temperatures, the cloudless skies in Ladakh guaranty over 300 sunny days per year which is the highest in the world. Therefore, there is plenty of sunshine for crops to grow even in winter, provided that they can be prevented from freezing. Various agencies are engaged in the research and development of protected cultivation of vegetables particularly during freezing winters to augment fresh food supply to the inhabitants. The present circumstances and priorities in the region need to be expanded for furthering the technologies to achieve self sufficiency.

Carbon mineralization in the soils under different cover crops and residue management in an intensive protected vegetable cultivation

Continuous cropping under plastic greenhouses, a common practice in intensive Chinese vegetable production systems, has led to the decline of soil productivity and crop yields. A 4-year greenhouse experiment on cucumber double-cropping systems was conducted in Changping country, Beijing, China, to investigate the effects of summer cover crops and residue management on soil microbial biomass carbon (MBC), C mineralization and cucumber yield. The treatments included sweet corn with residue removal after harvest (SR), sweet corn with residue incorporation after harvest (SI), common bean with residue removal after harvest (CR), common bean with residue incorporation after harvest (CI), Garland chrysanthemum and edible amaranth as summer cover crops (GR), and bare fallow during the summer period (Control). The experiment was a randomized complete block design with three replicates. C mineralization was analyzed by trapping the respired CO 2 using air-tight Mason jars containing NaOH vials. After 4 years of the trial, the treatments SR, SI and GR showed significantly ( P < 0.05) higher levels of potentially mineralized readily available carbon, C a (μg CO 2-C g −1), than control. The C a values for residue retention treatments were significantly related to the biomass inputs for both sweet corn- ( r = 0.981; P < 0.01) and common bean-related ( r = 0.994; P < 0.01) treatments. Generally, the SI and GR treatments showed greater cumulative C mineralization (CCM) than the other treatments. The relatively low CCM:MBC observed for the SI and GR treatments were significantly ( P < 0.05) related to increased cucumber fruit yields from 2005 to 2008. On the contrary, the CR and CI treatments resulted in significant declines in cucumber fruit yields over the same time periods. The responses of cucumber yields to cover crop treatments were related to the dynamics of soil C. These results suggested that the treatments SI and GR could increase C sequestration and improve soil productivity. Further research is required to test how much loss of C (SOC) occurs from the soil due to the protected cultivation using the in situ testing method.

Caracterização do modelo de cultivo protegido em Manaus com ênfase na produção de pimentão

O cultivo protegido de oleráceas é uma atividade em expansão no Amazonas. Várias são as vantagens em comparação ao cultivo sob condições de campo: colheita durante o ano todo, precocidade, aumento de produtividade e melhoria da qualidade dos produtos. O objetivo deste trabalho foi caracterizar o modelo de cultivo protegido utilizado em Iranduba, região de Manaus, com ênfase na produção de pimentão. Com base nas respostas obtidas em um questionário aplicado a nove produtores da região, verificou-se que 67% dos produtores entrevistados nunca tinham produzido hortaliças anteriormente e que a maioria utiliza casa-de-vegetação do tipo capela convectiva, com tamanho variando entre 160 e 495 m², a um custo de R$ 7,30 a 10,0 por m². A área média cultivada foi de 0,68 ha por produtor. O pimentão é a hortaliça predominante nas casas-de-vegetação. Para o seu cultivo, apenas 22% dos entrevistados realizaram análise de solo e calagem. Ainda assim, as quantidades de calcário e adubos utilizadas não são baseadas na análise. O solo é preparado mecanicamente por 89% dos entrevistados e todos utilizam gotejamento e fertirrigação. A água é proveniente de poços artesianos, mas não é feita análise da sua adequação à atividade. Pragas e doenças são controladas utilizando os agrotóxicos disponíveis no mercado, não raro nas mesmas dosagens e aplicações recomendadas para o cultivo convencional. A produtividade de pimentão no primeiro plantio atinge 125 t ha-1, com queda brusca, de até 40%, a partir do segundo plantio. Enquanto metade dos produtores entrega a produção a atravessadores, a outra metade comercializa em feiras e supermercados. Apesar de enfrentarem diversos desafios (assistência técnica deficiente, alto custo e baixa durabilidade das estruturas, falta de cultivares adaptadas ao clima local, indefinição de práticas de condução das lavouras), 67% dos produtores entrevistados gostariam de ampliar a área com cultivo protegido.