Showing papers on "Polyculture published in 2004"

Litter fall, litter stocks and decomposition rates in rainforest and agroforestry sites in central Amazonia

Abstract: The sustainability of agroforestry systems in Amazonia was assessed from their litter dynamics and decomposition. Litter fall and litter stocks were determined from July 1997 to March 1999 in four sites in central Amazonia: a primary rainforest, a 13-year-old secondary forest, and two sites of a polyculture forestry system which consisted of four planted tree species of commercial use amidst upcoming secondary growth. The average annual litter fall in the undisturbed primary rainforest (FLO) was 8.4 t ha−1 year−1, which is within the range of litter fall in other rainforests in the region. It was similar in one of the two polyculture sites (8.3 t ha−1 year−1), but lower in the secondary forest and in the second polyculture site. In the litter fall in secondary forest and agroforestry sites, the leaf portion was higher (76–82% of total litter fall) than in FLO, due to reduced fine matter and wood fall. Leaf litter fall variability was much lower in the plantation sites than in the forests, which is explained by the much more homogeneous stand structure of the plantations. The quality of the produced litter, measured as C/N ratio, differed significantly between the primary forest site and one polyculture and the secondary forest site. The cumulative input of nitrogen through litter fall was 144 kg ha−1 year−1 in FLO, and 91–112 kg ha−1 year−1 in the polycultures and the secondary forest. Litter fall was not correlated with soil parameters, but had a significant linear regression with canopy closure. For the primary rainforest, litter fall was also (inversely) correlated with monthly rainfall. Litter fall was higher in the first year (1997–1998; an El Nino period) than in 1998–1999. Litter stocks on the forest floor were highest in the secondary forest (24.7 t ha−1), and much lower in the polyculture sites (15.1–16.2 t ha−1) and the primary forest (12.0 t ha−1). There were no differences in the relative N content (C/N ratio) of the litter stocks between the sites, but the larger stocks led to higher absolute N contents in the litter layer in the secondary forest. From the monthly values of litter stocks (S) and litter fall (P), the decomposition coefficient k e=P/S was calculated, which was, on average, highest for the primary forest (0.059), followed by the polyculture systems (0.040–0.042), and by the secondary forest (0.024). Thus, due to low decomposition rates, the secondary forest site showed large litter accumulations in spite of a relatively low litter fall. In contrast, the primary forest showed high litter fall but low stocks, due to high decomposition rates. The decomposition coefficients of the polyculture systems ranged between the primary and the secondary forest. The reduced decomposition rates in the man-managed agroecosystems indicate quantitative and/or qualitative changes in the decomposer communities of these systems that lead to a higher build-up of litter stocks on the forest floor. However, the decomposer systems in the polyculture sites still were more functional than in the site of non-managed secondary growth. Thus, from a soil biological viewpoint, ecologically sustainable low-input agroforestry in Amazonia will benefit from the application of these polyculture systems.

Effects of algal and herbivore diversity on the partitioning of biomass within and among trophic levels

Abstract: Factorial manipulations of biodiversity on different trophic levels can reveal the mechanisms that govern how biomass is partitioned within and among trophic levels. Here I report results of a laboratory microcosm experiment crossing eight algal compositions (seven monocultures and a polyculture of all seven species) with five ciliate herbivore compositions (no herbivores, three monocultures, and a polyculture of all three species). Microcosms allowed comparison of short-, medium-, and long-term (dozens of generations) results. Niche differentiation allowed competing algae to coexist in the absence of herbivores. Surprisingly, algal polycultures produced more biomass than the most productive monocultures only in the medium term. A temporally variable relationship between the productivity of diverse and depauparate algal assemblages might reflect changes in competitive mechanisms over time, and/or transient dynamics, and contrasts with the predictions of simple competition models. Herbivores had little eff...

Effects of adding different proportions of the small fish punti (Puntius sophore) and mola (Amblypharyngodon mola) to a polyculture of large carp

Abstract: This experiment was carried out in the framework of a project to develop a viable fish polyculture technology under Bangladeshi conditions that allows simultaneous fish production of small indigenous species for the farmers' family consumption and of large carp species as a cash crop. The objectives of this experiment were to assess the effects of adding punti and mola in different proportions on the large carp and on the environment, and to assess the effects of punti on mola and mola on punti. The polyculture included the large carp rohu, catla and common carp (as cash crop fish), and the small indigenous fish punti and mola (as food for the small-scale farmer family). The total large carp stocking density was 10 000 fish ha−1, at a species ratio of 1:1:1. The total small fish stocking densities were 0 in the control and 30 000 punti and mola ha−1 in the treatments, these at rates 2:1, 1:1 and 1:2. Stocking punti and mola at the density and all ratios tested were viable solutions to obtain simultaneously large carp cash crops and small fish to feed the farmer's family. Statistically marginal differences in large carp production were obtained in stocking small fish in the different proportions. These marginal differences could be explained by food competition between punti and common carp and between mola and rohu, which had different outcomes depending on the proportions of the small fish stocked. Stocking punti and mola at a 1:1 ratio would result in more small fish for the farmer's family, while the individual size of rohu, the most expensive large carp, would be somewhat smaller, but not necessarily small enough to decrease its selling price. Stocking one of the small fish in higher proportion than the other (2:1 or 1:2) would result in less mola for the family consumption, while harvesting of common carp would be somewhat lower and of smaller fish. Since common carp is the cheapest of the large carps, this small reduction would not necessarily affect the family income in an important way. With these results, farmers would now be able to reorganize their stocking practices with large carps and small fish and decide the appropriate small fish stocking ratios to meet their needs.

Produtos agrícolas e florestais como alimento suplementar de tambaqui em policultivo com jaraqui

Abstract: The objective of this paper was to evaluate the performance of tambaqui (Colossoma macropomum) in a polyculture trial with jaraqui (Semaprochilodus insignis), using agricultural and forest products as supplementary feeding for tambaqui. Two ponds, measuring 644 m2 (Pond A, associated with pigs) and 1,075 m2 (Pond B, non associated), were stocked with 0.5 tambaqui/m2 and 0.1 jaraqui/m2. After 371 days, tambaqui showed a mean growth from 18.6±4.5 g to 997.1±195.08 g in Pond A, and from 81.4±18.8 g to 519.9±191.7 g in Pond B. Feeding management of Pond A may be a sustainable alternative of tambaqui production in substitution to commercial rations.

Polyculture of grass carp and nile tilapia with napier grass as the sole nutrient input in the subtropical climate of nepal

Abstract: An experiment was conducted in outdoor concrete tanks (4.9 m x 4.8 m x 1.75 m) at the Institute of Agriculture and Animal Science (IAAS) of Nepal to evaluate the growth of grass carp and Nile tilapia fed with napier grass in polyculture, to evaluate water quality regimes of pond water, to determine the compositions of foods consumed by Nile tilapia, and to determine the optimal ratio of grass carp to Nile tilapia in polyculture. The experiment was laid out in a completely randomized design with five treatments replicated thrice. Five stocking ratios of grass carp to Nile tilapia were tested: (1) grass carp only at 0.5 fish/m (control); (2) grass carp at 0.5 fish/m plus tilapia at 0.25 fish/m; (3) grass carp at 0.5 fish/m plus tilapia at 0.5 fish/m; (4) grass carp at 0.5 fish/m plus tilapia at 1 fish/m; and (5) grass carp at 0.5 fish/m plus tilapia at 2 fish/m. Grass carp fingerlings (39.3±2.3 – 46.6±0.2 g) were stocked on 26 May 2002, while mixed-sex Nile tilapia fingerlings (9.0±0.1 – 10.0±0.2 g) were stocked 6 days later. Chopped fresh napier grass leaf was the sole nutrient input and provided ad libitum daily in the morning. Mass mortality of grass carp (100%) occurred in all three replications of the monoculture (treatment 1) during the twelfth week (81 days) of the experimental period, however, survival of grass carp was not significantly different among the polyculture treatments (treatments 2 through 5) (P > 0.05). At harvest, the mean weights and daily weight gains of grass carp in treatment 3 were significantly greater than those in other polyculture treatments (P 0.05). There were no significant differences in all measured water quality parameters. Gut analyses showed that grass carp consumed grass only while Nile tilapia consumed diversified food items including feces of grass carp. The present study has showed that the optimal ratio of grass carp to Nile tilapia in polyculture fed napier grass is 1:1, i.e., grass carp at 0.5 fish/m plus Nile tilapia at 0.5 fish/m. The present study has indicated that the addition of Nile tilapia to the grass carp tanks fed napier grass as the sole nutrient input is a low-cost culture system, which can efficiently utilize available resources, reuse wastes derived from grass carp, augment total fish production.

In Defense of Crop Monoculture

Abstract: Because yields typically decline, crop monoculture is commonly considered as not sustainable. This yield decline is due largely to soilborne plant pathogens adapted to/specialized for the roots of the crop. For high-value fruit and vegetable crops, yields are maintained with monoculture using soil fumigation or soil solarization. Soils can also be sanitized by flooding, which may account for the success of paddy rice monocultures. Our work in the U.S. Pacific Northwest has focused on four root and crown diseases of wheat and barley, namely take-all caused by Gaeumannomyces graminis var. tritici, Fusarium crown rot caused by Fusarium culmorum and Fusarium pseudograminearum, Rhizoctonia root rot caused by Rhizoctonia solani AG8 and R. oryzae, and Pythium root rot caused by several Pythium species. Herein, we describe a remarkable and apparently wide-spread microbiological control (disease suppression) in the rhizosphere that is responsible for the well-documented decline of take-all and coordinate increase in crop yield following one or more outbreaks of the disease and continued monoculture of wheat or barley. Since this disease suppression is specific for take-all, other strategies are under development for control of the other three root and crown diseases with wheat-intensive cropping systems, including in direct-seed systems. The strategies include the development of transgenic resistance in barley to Rhizoctonia root rot using the ThEn42 gene from Trichoderma harzianum for production of a 42-Kda endochitinase, selection of wheat cultivars for tolerance to Fusarium crown rot, and use of a systemic seed-treatment chemicals and current-year seed for seedling protection against Pythium root rot. Introduction Crop rotation, which we define as the practice of growing different crops in sequence in the same field, is nearly as old as agriculture itself and remains the centerpiece of most cropping systems worldwide. Crop monoculture, which we define as the practice of replanting the same crop species in the same field, with no break to a different crop, has an equally long but less successful history, except for some high-value fruit and vegetable crops grown with the aid of soil fumigation or soil solarization, and also possibly for paddy rice. “Crop monoculture” is also used to describe large areas planted to the same crop species, e.g. the vast area planted to wheat each year in the North American Great Plains. For purposes of our defense of crop monoculture, like crop rotation, we mean crop monoculture in the temporal and not the spatial sense. Growers that practice crop monoculture generally do so for economic reasons. The selected crop is the most profitable and any profitability loss from yield declines are less than that which occurs from any rotational options available. In these situations, the ability to minimize the losses associated with monoculture can provide the best option to increase productivity and profitability. Many names have been given to the phenomenon of yield decline with monoculture, including replant problem, autotoxicty, and monoculture injury. Even perennial crops such as alfalfa and grasses are prone to show yield (or stand) decline over time, typically starting in the third or fourth year following their establishment. Similarly with annual crops, yields typically decline starting in the third or fourth year of the monoculture, although some yield decline may occur already in the second year of monoculture (Cook and Baker, 1983). Because of these yield declines, crop monoculture is commonly considered as not sustainable. Crop rotation, like tillage, is an invention of agriculture. Indeed, annual plants in the wild reseed themselves in more or less the same places year after year—and without tillage. The occurrence of wild plants in polycultures could provide a kind of rotational benefit in cases where the seeds of one species happen to fall on the site occupied the previous year by a different species. In the case of wheat, the

Performance of Component Species in Three Apple-Berry Polyculture Systems

Abstract: The commercial and ornamental potential of three apple-berry polyculture systems was ascertained by monitoring the above-ground performance of component species in plots of 'GoldRush' apple (Malus xdomestica Borkh.) trees on M.7 rootstock cropped with either blackberry (Rubus spp. L. 'Navaho'), edible honeysuckle (Lonicera caerulea L. 'Blue Belle' and 'Blue Velvet'), or jostaberry (Ribes nidigrolaria Bauer 'Josta') as understory plants. Polyculture plots and corresponding monoculture controls were established in 1999, with berry plants at recommended (R) or close [(C), half-recommended] spacings. Blackberries and jostaberries planted in monoculture at recommended spacings [i.e., control (R) plots] amassed dry weights >1 kg/plant by Fall 2001; the dry weight of edible honeysuckle from comparable plots was slightly >0.3 kg/plant. In 2001, blackberry yield (3.1 kg/plant) and fruit weight (3.4 g) were typical of 'Navaho' plantings of similar age, whereas jostaberry was only moderately productive (yield = 286 g/plant; fruit weight = 1.4 g). Edible honeysuckle productivity (yield = 13 g/plant, fruit weight = 0.5 g) was minimal, due to disparate flowering phenology between cultivars. 'GoldRush' apple growth and productivity (yield = 25 kg/tree; fruit weight = 158 g) was consistent with values expected for trees of similar age. Blackberry plant dry weights were reduced by 20% to 33% when planted at close spacing, whereas blackberry yields were reduced 35% to 38% when grown in polyculture with apple. Both polyculture and plant spacing significantly reduced jostaberry dry weights (i.e., 12% and 24%, respectively) relative to the control, but neither significantly affected jostaberry yield. Conversely, both close-spaced planting and the presence of an apple tree improved the yield of edible honeysuckle. Apple performance was not affected by the presence of an edible honeysuckle understory, but apple growth factors were reduced in blackberry and jostaberry polycultures by as much as 65%. Apple bloom, fruit set, and yield were also significantly reduced in apple-blackberry and apple-jostaberry plots, with fruit numbers/tree averaging <5 in all except the apple-blackberry (C) treatment. None of the polyculture treatments studied were suitable for profitable fruit production. However, each of the polyculture constituents exhibited unique, beneficial attributes with respect to their use as components within an edible landscape.

Optimization of culture model in seawater pond:concepts, principles and methods

Abstract: Currently used seawater pond culture models are evaluated, and principles and methods in optimizing pond culture model are discussed in the present paper. The author indicates that application of the traditional polyculture has been limited in single pond. Inputted nutrients such as feed and fertilizer can't be efficiently utilized by animals cultured in a pond with the traditional polyculture, resulting in huge waste discharge, which is regarded as a pollution source to coastal regions. The author suggests it should be possible to put several seawater ponds with different stocking structures together and optimize stocking and management systemically. Compared with the traditionally polycultured seawater ponds, ecological benefits and nutrients transport in the systemically optimized ponds would be amplified. The production performance of the systemically optimized ponds, therefore, would be increased and their pollution would be reduced.

Review: Production of Gracilaria parvispora in two-phase polyculture systems in relation to nutrient requirements and uptake

Abstract: 3 Abstract Gracilaria parvispora Abbott is highly valued in Hawaiian seafood markets. Due to the over-harvesting of natural beds. G. parvispora is scarce on the open reef ; and harvesting is strictly regulated. On Molokai, Hawaii, a community-based operation was established to develop a sustainable, integrated culture system for this species. Previous research suggested that ammonium was the limiting factor for sufficient growth on the reef. Therefore, on Molokai, a polyculture system was developed using fish/shrimp ef- fluent to load thalli with nitrogen before placement in a low-nutrient lagoon for grow- out. The research described here demonstrates how small-scale, commercial culture of seaweed can be successfully integrated with the production of fish and shrimp. Two benefits of a two-phase polyculture system are: 1) a waste product from the first phase (i.e. ammonia nitrogen) becomes a resource for the second phase and 2) integrated sys- tems are financially more stable because of improved cash-flow and product diversifica- tion. A modest biomass of fish can support a substantial production of seaweed. The type of cage-based, polyculture system developed on Molokai could be applicable to other rural coastal areas.

Cultivation of prawn in polyculture with some species of Indian and Chinese major carps

Abstract: The freshwater prawn Macrobrachium rosenbergii (de Man) was cultivated in polyculture with Indian and Chinese major carps for two successive years The densities of prawn were 6000,8000 and 10,000 juveniles / ha with a constant fish density of 5,000 fish fingerlings / ha The fish species were silver carp (35%), catla (15%), mrigal (20%) in the first year and in the second year silver carp, catla, rohu, mrigal, grass carp and black carp in the ratio of 30:15:34:5:15:1, respectively Highest production of prawn and fish were 122 kg / ha and 4200 kg / ha / yr in the first year and 96 kg / ha and 3945 kg / ha / yr in the second year The low production of prawn might be hampered by the low temperature However, cultivation of prawn with Indian and Chinese major carps should be made in overwintering season and low prawn density should be maintained in polyculture system of M rosenbergii with fish

Giant freshwater prawn culture in Indonesia

Abstract: Indonesia is one of the countries that have high levels of biological diversity in terms of freshwater fishes, the country’s rich biological resources, characterized by a high level of endemism. About 30 endemic species of freshwater fishes are found in Sumatera, 149 species in Kalimantan, 12 species in Java, and 52 species in Sulawesi (Anonym, 1994; Kottelat et al.,1993). The country’s total freshwater area is 55 million ha consisting of lakes, dams, swamps and other water bodies. The potential area for freshwater pond fish culture is estimated at 233,124 ha with a production of 334,085 mt/year (DGF, Indonesia. 2001), of which about 5140 mt comprises the giant freshwater prawn.

The cause of the decrease of population dynamic of Typhlodromus bambusae Ehara in moso bamboo forest

Abstract: This paper dealt with the studies on outbreaks phenomenon of pest mites of moso bamboo (Phyllostaychs pubescens) forests in south of China The result showed that the total pest mites in monoculture forests was on an average 28929% as high as that in polyculture stands Thphlodromus bambusae Ehara, a natural enemy, in the polyculture forests was on an average 2625% as high as that in the monoculture The proportion of pest mites and nature enemy in the monoculture forests was on an average 1∶118,but in the polyculture was on an average 1∶13 The result from these research showed that the outbreaks of pest mites in bamboo forests was caused by fatal disruption of the stable interaction between predators and their 3 prey species in the fields through farming activity such as removal of the plants under bamboo forests For example, the population of Schizotetranycus nanjingensis Ma Yuan had been regulated by T bambusae, where another spider mite species S miscanthi Saito in the host plant (Miscanthus sp) is very important prey species for keeping the population of T bambusae Monoculture may reduce the abundance of natural enemies of phytophagous mites by reducing alternative habitats and food for them, which indirectly contribute to the outbreake of pest mites on bamboo in Fujian Province

Polyculture of Shrimp-Fish-Shellfish-Algae in Water Recirculating System with Group Ponds

Abstract: A polyculture of shrimp-fish-shellfish-algae in water recirculating system with group ponds ecologically optimum culture pattern was designed in this paper The system comprises four functionally different culture areas: prawn culturing area, fish culturingarea area, shellfish culturing area and large-scale marine algae cultivating area, additionally, one water treatment area, and one emergency drainage canal Bio-manipulation of water quality was achieved by stocking different culture organisms in different ponds within the closed circulatory system Results indicated that contents of suspensions, COD value and amounts of ammoniated nitrogen were significantly lower than those in monoculture control ponds (t test, P001) The wastewater was no longer eutrophicated (E1) Besides obtaining 0667 kg prawns, 0037 kg tilapia, 0738 kg oyster, 0437 kg Gracilaria were also produced by input of prown feed of per kilogram, tenuistipitata and feed conversion ratio and economic benefits increase notably It has advantages, such as the noture of preventing disease, environmental protection, efficiency, etc

Mixed Function Oxidase Activity and Organochlorine Levels in Farmed Sharpsnout Seabream (Diplodus puntazzo) from Two Intensive Aquaculture Facilities

Abstract: Mixed function oxidase (MFO) activities and organochlorine levels were investigated in liver of farmed sharpsnout seabream bred in two intensive facilities, a sea farm and a land-based farm. The aim of this study is to investigate how different facility locations and breeding conditions might affect fish metabolic capabilities and accumulation of toxic chemicals in farmed sharpsnout seabream. The differences between breeding two or more fish species in the same cage or tank known as polyculture, and monoculture (1 species) were also investigated. The results showed that both facility location (sea and land) as well as breeding systems (polyculture and monoculture) might be responsible for the differences observed in both MFO enzyme activity and organochlorine levels. Significantly higher activities of two metabolizing enzymes such as 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (B(a)PMO) were in fact recorded in land-based farmed fish than in sea farmed ones, and much higher in those from polyculture than in monoculture (p < 0.05). By contrast, the highest levels of dichlorodiphenyldichloroethilene (pp′DDE) and polychlorinated biphenyls (PCBs as Aroclor 1260) were measured in sea-farmed fish, except for hexachlorobenzene (HCB), which gave higher levels in land-based farmed fishes. No significant differences were observed between monoculture and polyculture in p,p′DDE and PCBs levels except for p,p′DDE which was significantly higher in monoculture than in polyculture (p < 0.05) in fish reared in tanks. Finally significantly higher HCB levels were measured in fish reared in monoculture in tanks (p < 0.05) and in polyculture in cages (p < 0.05). The low TEQ values obtained for PCB congeners at liver level indicated no concern for fish health.

Polyculture production of juvenile fishes for survival in nature

Abstract: Production of seed for stock enhancement projects requires consideration of the behavioural quality of the animals to be released in the wild. Our approach to improving behavioural quality of hatchery fish is to raise them in polyculture with the plants or animals that fish normally utilize as shelter in nature. Results suggest that such ‘naturalized’ systems provide a broad improvement in behaviour as both predator avoidance and feeding skills were improved relative to control hatchery fish. In addition fish in a naturalized system grew better and were more tolerant of stress than were fish reared by traditional hatchery methods. We hypothesize that the spatial heterogeneity of our ‘naturalized’ systems provided training in both hiding and seeking and that these activities improved feed conversion and stress tolerance.

Current status of polyculture and rotation culture in Chinese mariculture industry

Abstract: The status of polyculture and rotational culture in Chinese marine life is reviewed. Some successful experience is summarized.