•Increased density resulted in significantly increased total shrimp harvest weight.•Growth rate was significantly lower and FCR was higher in high density tanks.•Substrate addition did not ...significantly impact shrimp performance or water quality.•Nitrate accumulation over time was exceptionally low.
The use of artificial substrates in shrimp aquaculture may allow for production of shrimp at increased densities while providing a growth medium for microbes that assist with water quality processes and provide supplemental nutrition for shrimp. Greenhouse-based shrimp production systems can extend the shrimp production season in temperate climates while conserving water and energy. For this study, we evaluated the effects of providing extra substrate and shrimp density on water quality and shrimp production in greenhouse-based biofloc systems. Four 11-m3, wood framed, and rubber-lined tanks were constructed in each of four high tunnel greenhouses (for a total of 16 tanks). Four treatments were evaluated: high-density stocking with substrate (HDS), high-density stocking with no substrate (HDNS), low-density stocking with substrate (LDS), and low-density stocking with no substrate (LDNS). Each treatment was randomly assigned to one tank in each tunnel to block for location. No artificial heat was used, and shrimp were grown for 120 days. High-density systems were stocked at 200 shrimp/m³ while low-density tanks had 100 shrimp/m³. Adding substrate increased total in-tank surface area by 13.4%. The addition of substrate had no significant effect on any shrimp production or standard water quality parameters. Shrimp had significantly greater final weight, faster growth rate, and lower feed conversion rate in low-density treatments (P ≤ 0.02 for all). Total shrimp biomass production was significantly higher in high-density treatments (HD: 4.0 kg/m3; LD: 2.3 kg/m3; P < 0.05). There were no significant differences in survival between densities (HD: 91.3%; LD: 94.5%; P = 0.43). Peak and overall mean nitrite levels were significantly higher in high-density treatments compared to low-density treatments. Dissolved oxygen levels and pH over the course of the study were significantly lower in high-density treatments, likely due to increased respiration rates in the water column. This project shows the feasibility of shrimp production in temperate climates with no artificial heat using high tunnel greenhouses, few impacts of added substrate on shrimp production, and increased shrimp density can result in much larger harvests with few negative impacts on production metrics.
The study was carried out to investigate constraints and determinants of high tunnels adoption for tomato production in the North-East District of Botswana, using household survey data sourced ...directly from 116 horticultural farmers during the months of May and June 2017. Descriptive statistics and a binary probit regression model were employed to analyze constraints and determinants of high tunnels adoption for tomato production. The prohibitive cost of high tunnels, inadequate knowledge on high tunnels, inadequate capital and markets were identified as major constraints that hinder high tunnels adoption. The adoption of high tunnels was found to be positively influenced by years of education, access to extension services and farm size. The findings suggest that encouraging tunnel designers to consider constructing the structure using local materials could be ideal to cut down on the startup cost. Strengthening extension service and re-engineering of the current extension system is necessary to improve the adoption rate of the technology.
Int. J. Agril. Res. Innov. Tech. 10(2): 100-109, December 2020
The consumer demand for locally grown fresh produce is continuously increasing in the United States. The high tunnel systems have been successfully utilized by small acreage growers for local ...production. Consumers are typically assessing appearance, freshness, flavor and aroma when purchasing produce. A common perception is that locally grown produce tastes better than nonlocal. However, there is not much evidence for supporting this claim. The objective of this study was to identify consumer acceptability and the sensory characteristics/differences of locally grown spinach in open field or in high tunnel and nonlocal commercially grown spinach. Spinach, Spinacia oleracea cv. “Corvair” was grown in open field and in high tunnel at Kansas State Univ. Olathe Horticulture Research and Extension Center (OHREC) in spring 2017 and the commercially grown spinach was purchased at a local retail store. A consumer study (n = 205) was conducted at Kansas State Univ., Olathe campus, and a descriptive sensory analysis was conducted by a highly trained descriptive analysis panel in the Center for Sensory Analysis and Consumer Behavior at Kansas State Univ., Manhattan campus, in spring 2017. The consumer test showed that high tunnel spinach scored significantly higher in overall liking (P < 0.0001), flavor liking (P < 0.0001), and texture liking (P < 0.05) when compared to open field and store purchased spinach. Descriptive analysis showed that locally grown spinach had higher intensity of attributes that indicate premium quality, such as green color and green/spinach flavors. Our results indicate that locally grown spinach was preferred from the consumers for its high organoleptic quality.
Practical Application
Locally grown spinach demonstrated high intensity in a set of sensory attributes that suggest a product with premium organoleptic quality. Correspondingly to these results, consumers liked spinach produced locally in high tunnels the most. The results of this study can be used for developing marketing strategies that are aiming specifically to the consumer niche that is seeking fresh produce of high organoleptic quality.
Vegetable production systems are typically tillage- and input-intensive, though they may vary widely in production practices utilized. Improved understanding of soil water and nitrogen (N) processes ...with the use of agroecosystem models may aid in the optimization of crop yields and reduction of N losses. The objectives of this study were to (1) apply the RZ-SHAW model to diversified vegetable systems of varying production intensity, and (2) to elucidate soil N processes key loss pathways to inform opportunities for improving N cycling and sustainable intensification in these systems. The systems included conventional (CONV), low input organic (LI), and organic high tunnel (HT) vegetable systems. Soil water content and temperature were simulated well (rRMSE < 0.30) in all systems. Simulated soil NO
3
¯-N content was closer to measured values in the CONV than other systems. On average, the soil NO
3
¯-N content was underpredicted by 8 kg N ha
−1
in the 0–0.15 m, and 5 kg N ha
−1
in the 0.30–0.50 m soil layer in the LI system. In all systems, simulated daily N
2
O flux followed the trends in the measured values, but model predicted greater peaks than measured. Nitrate leaching was the greatest N loss pathway in all systems, though timing and driving factors varied by system. Asynchrony between N mineralization and crop uptake was observed throughout the LI rotation, indicating opportunities for targeted N and irrigation inputs to increase crop yields. Simulation results indicate the need for additional study of soil microbial and N processes in HT systems.
High-tunnel (HT) systems have been shown to effectively improve yields, fruit quality and profitability. In order to maximize returns on investment, HTs are frequently planted successively with both ...winter and summer cash crops and may include >2 crop cycles per year in some climates. The intense cultivation strategies used in HT systems necessitate increased tillage and nutrient demands posing challenges for soil health, environmental quality and long-term economic sustainability, particularly among organic growers. Seasonal rotations that incorporate fertility-building cover crops, such as legumes and other green manures, have the potential to build soil organic matter, improve crop yield and reduce applications of animal manure and/or compost. The economic impact of cover crop use in HT production systems poses important implications for organic growers. In this study, we present three partial budget analyses to quantify the economic benefits from a leguminous winter cover crop–tomato cash crop rotation in HTs across three regions. Data used in the economic analysis come from multi-year organic HT field trials in Kansas (2016–2019), Kentucky (2016–2019) and Minnesota (2016–2020). Direct financial benefits from hairy vetch (Vicia villosa) cover crop N credits were observed but not sufficient to offset the direct and indirect costs of the cover crop practice. A winter cover crop used in organic HT vegetable systems results in negative financial benefits to producers even with conservation incentive payments. These results highlight challenges for organic growers who are required under the USDA National Organic Program to incorporate soil building practices as part of their rotation schedule. The findings will also be of interest to policy makers as they refine cost-share offerings and programming to incentivize cover crop adoption as a conservation strategy.
In temperate climates, there has been an increasing interest by fruit growers to implement the use of high tunnels, using a variety of coverings, to extend the season for fruit production. High ...tunnels also provide an opportunity to enhance insect pest management, via physical exclusion, and thus support reductions in insecticide use. Due to increasing pest pressure by the Japanese beetle, Popillia japonica Newman, in Midwest U.S. raspberry, a 3-year study (2017−2019) was conducted to evaluate the efficacy of selected high tunnel coverings to suppress adult beetle populations and minimize adult feeding injury. During each year of the study, P. japonica adult beetles were significantly reduced under poly-based coverings, with the ends open, and when a fine, nylon-mesh was used to cover the ends (p < 0.05). The poly-based covering also resulted in moderately higher ambient temperatures, which may have influenced beetle movement, including a “repellency effect” that encouraged beetles to exit the high tunnel structures. Although P. japonica adults are known to feed on raspberry flower clusters, including fruit, the majority (73−92%) of beetle feeding in this study was observed on the foliage. The impact of high tunnels on P. japonica are discussed within the context of developing sustainable Integrated Pest Management (IPM) programs for raspberry production.
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