Potential Agricultural Value Research Articles

Post-treatment of high-rate activated sludge effluent via zeolite adsorption and recovery of ammonium-nitrogen as alternative fertilising products

This study investigates the potential to connect nutrient flows between wastewater treatment and agriculture through a two-stage nitrogen (N) recovery system composed of high-rate activated sludge treatment in contact stabilisation mode (HRAS/CS) and column adsorption with zeolite. The HRAS/CS process removes organic matter and suspended solids in wastewater, leaving N behind in the effluent. The N was successfully recovered with the zeolite column under different scenarios, generating N and K-rich by-products. The regeneration effluent from the zeolite column with KCl contained 60–845 mg NH4+-N/L and 1.6–14.3 g K/L, having potential for use as fertigation water. The N-saturated zeolite contained 1.5–8.4 mg N/g and 14.3–19.3 mg K/g of the product fresh weight and low contaminant content, making it potentially eligible as various fertilising products. Adsorption can thus concentrate N from HRAS/CS effluent and produce by-products with potential agricultural value while meeting chemical oxygen demand and total nitrogen discharge standards.

Characterization of charcoal and firewood ash for use in African peri-urban agriculture

BackgroundAmple quantities of ashes generated from domestic biomass energy combustion in Ghanaian kitchens are currently disposed of despite their potential agricultural value. This study aimed to investigate the potential agricultural value of charcoal and firewood ashes in terms of differences in the chemical and mineralogical compositions, and to identify the suitability of aqua regia, H2SO4, vinegar and distilled water to extract plant nutrients (Ca, Mg, K, Na, and P). The chemical compositions were determined by atomic absorption spectrometry after extractions with aqua regia, H2SO4, vinegar and distilled water while mineralogy was determined by X-ray powder diffraction.ResultsThe charcoal ash had 0.2 units, 13 ds m−1, and 7% higher (P < 0.05) pH, EC, and CCE, respectively, than the firewood ash, whereas the latter had 6, 17, 43, and 139 µg g−1 higher (P < 0.05) As, Cu, Mg, and Zn contents, respectively, and more minerals with 86% being Mg-rich. Calcite and calcium oxide were the dominant minerals occurring in both ashes followed by calcium manganate (CaMnO3). Aqua regia and vinegar were suitable for Ca, acidic solutions for Mg, H2SO4 and aqua regia for P with Na and K being virtually soluble in all solutions. Lead, Mn, Ni, and Zn had values in the order of hundreds.ConclusionsAlthough the ashes differ, they both contain trace elements whose bioavailability may differ and may not necessarily lead to plant uptake after field application. This offers an opportunity for further research into the threshold trace element contents of wood ash and their relationship with plant uptake in different soil pH and soil types.

Distribution and Productivity of Naturalized Alfalfa in Mixed-Grass Prairie

Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-grass prairie on the Grand River National Grassland in South Dakota has potential agricultural value for the region. Despite this value, the distribution pattern of this alfalfa among and within native plant communities in the northern Great Plains is unknown. Field studies were conducted from 2003 through 2006 along topographic positions at two sites where yellow-flowered alfalfa was naturalized to evaluate the relationships of yellow-flowered alfalfa on biomass production, cover, species diversity, and alfalfa seedbank distribution characteristics. High yellow-flowered alfalfa cover (>50%) was associated with increased total biomass and occurred exclusively in swales and toeslopes that had silty loam soils. However, species diversity and non-alfalfa biomass were reduced when yellow-flowered alfalfa cover was high. Yellow-flowered alfalfa cover was lower and species richness was higher on backslopes and shoulder areas where sandy loam soils were present. A strong positive linear association existed between yellow-flowered alfalfa cover and alfalfa seedbank density (r values ranged from 0.76 to 0.82, P < 0.0001). Greater than 99% of the seeds were viable but germination rate was only 4%, indicating a high percentage of hard seed in this alfalfa population. Naturalized yellow-flowered alfalfa was a dominant component of a stable, low diversity plant community composed of mainly introduced species in rich soils of swales/toeslopes that contributed to forage production and quality in mixed-grass prairie in the northern Great Plains.

Enhancing Brassinosteroid Signaling via Overexpression of Tomato (Solanum lycopersicum) SlBRI1 Improves Major Agronomic Traits.

Brassinosteroids (BRs) play important roles in plant growth, development, and stress responses through the receptor, Brassinosteroid-insensitive 1 (BRI1), which perceives BRs and initiates BR signaling. There is considerable potential agricultural value in regulating BR signaling in crops. In this study, we investigated the effects of overexpressing the tomato (Solanum lycopersicum) BRI1 gene, SlBRI1, on major agronomic traits, such as seed germination, vegetative growth, fruit ethylene production, carotenoid accumulation, yield, and quality attributes. SlBRI1 overexpression enhanced the endogenous BR signaling intensity thereby increasing the seed germination rate, lateral root number, hypocotyl length, CO2 assimilation, plant height, and flower size. The transgenic plants also showed an increase in fruit yield and fruit number per plant, although the mean weight of individual fruit was reduced, compared with wild type. SlBRI1 overexpression also promoted fruit ripening and ethylene production, and caused an increase in levels of carotenoids, ascorbic acid, soluble solids, and soluble sugars during fruit ripening. An increased BR signaling intensity mediated by SlBRI1 overexpression was therefore positively correlated with carotenoid accumulation and fruit nutritional quality. Our results indicate that enhancing BR signaling by overexpression of SlBRI1 in tomato has the potential to improve multiple major agronomic traits.

Novel Genetic Variants of GA-Insensitive Rht-1 Genes in Hexaploid Wheat and Their Potential Agronomic Value

This study has found numerous novel genetic variants of GA-insensitive dwarfing genes with potential agricultural value for crop improvement. The cultivar, Spica is a tall genotype and possesses the wild-type genes of Rht-A1a, Rht-B1a and Rht-D1a. The cultivar Quarrion possesses a null mutant in the DELLA motif in each of the 3 genomes. This is a first report of a null mutant of Rht-A1. In addition, novel null mutants which differ from reported null alleles of Rht-B1b, Rht-B1e and Rht-D1b have been found in Quarrion, Carnamah and Whistler. The accession, Aus1408 has an allele of Rht-B1 with a mutation in the conserved ‘TVHYNP’ N-terminal signal binding domain with possible implications on its sensitivity to GA. Mutations in the conserved C-terminal GRAS domain of Rht-A1 alleles with possible effects on expression have been found in WW1842, Quarrion and Drysdale. Genetic variants with putative spliceosomal introns in the GRAS domain have been found in all accessions except Spica. Genome-specific cis-sequences about 124 bp upstream of the start codon of the Rht-1 gene have been identified for each of the three genomes.

The Impact of a Liberalised Trade Regime on the Potential for Agricultural Value Addition in Uganda

Uganda is one of the LDCs in Africa whose economy is heavily dependent on agriculture for exports, GDP and domestic employment. However, Uganda has implemented a liberalised agricultural trade regime since the 1990s, and by 2005, Uganda was considered one of the most liberalised economies in Africa. Yet Uganda's experience seems to contradict recent evidence regarding import liberalisation, economic growth and effective integration in the global economy, which suggests that liberalisation, should follow rather than precede sustained periods of economic growth and should be gradual and sequenced. Uganda seems not to have followed that approach. This paper reports the findings of a study on Uganda's experience with import liberalisation of agricultural products and how this has impacted on agricultural value addition potential. The results show that liberalisation of the agricultural trade regime in Uganda has resulted in phenomenal growth in imports of agricultural products particularly the processed ones. The scope of the tariff lines has also expanded sharply. Secondly, almost all potential agricultural value addition possibilities were being supplied by competing imported products with import levels likely to increase. The locally produced value-added agricultural products had very limited competitive space and in many cases were already swamped by imported ones. Last but not least, agro-processing ventures seemed to have experienced declining competitiveness due to increased competition from agricultural imports resulting in declining demand and sales, market share and profitability. To reverse this trend, the study observes the need to accord additional protection to the agricultural sector and to implement specific measures to boost the competitiveness of agro-processing investments.

Potential value of someBromusspecies of the sectionCeratochloa

Abstract The paper discusses the potential agricultural value of 10 Bromus species in the section Ceratochloa. The species are bunch grasses poorly adapted to soils which are prone to waterlogging or are heavy‐textured, very acidic, or have moderate to high levels of aluminium. They are moderately deep‐rooted with good drought tolerance on better soils but require warm soil temperatures for reliable establishment. The seeds do not flow readily as they are generally large, light, and often have awns and fine hairs on the seed coat. The seed requires additional processing to be sown commercially. Forage is generally of high quality and palatability, and endophytic fungi are not a problem. Prairie grass (B. willdenowii Kunth) is a large‐tillered short‐lived, productive, winter‐active species demanding very high soil fertility. It requires a long rotation interval between grazings and has poor tolerance to close continuous grazing. This inflexibility limits its role on farms. Grazing brome (B. stamineus Desv.) is a fine‐tillered winter‐active, perennial, drought‐tolerant species with tolerance to close continuous grazing. This flexibility allows it to be used as a general‐purpose pasture. It is best adapted to milder winter climates but not to regions with less than 400 mm or more than 1000 mm annual rainfall. B. valdivianus Phil, is finer‐tillered and produces a denser sward with less winter growth, but otherwise is agronomically quite similar. Bromus burkartii Desv. is a fine‐tillered winter‐dormant perennial species with tolerance to close continuous grazing. It is potentially best adapted to colder winter climates such as in the mountain valleys of New Zealand and Tasmania. Annual forms of B. carinatus H. & A. with very high winter growth could be valuable in mediterranean zones of Australia. B. sitchensis may be valuable in cold winter regions. Three lesser known species B. leptoclados Nees., B. runssorensis K. Schum., and B. lithobius Trin. are also discussed briefly.

Growth of Plants on Soils from Two Metalliferous Sites in Rhodesia

The vascular plants of Rhodesia are fairly well known taxonomically but, although there are detailed geological maps of areas interesting to the mining industry, and the soils have been studied in most parts of actual or potential agricultural value, little has been written about edaphic influences on species distribution. The Flora Zambesiaca (Exell & Wild 1960-) mentions the apparent soil 'preferences' of certain species and Rattray (1960) reported that some grasses occur more frequently on certain soil types. There are relatively large areas of highly metalliferous soils. Wild (1965, 1968, 1970) and Jacobsen (1967, 1968) have drawn attention to the over-riding effects on their distinctive vegetation of parent rocks containing copper or nickel. However, in a detailed study of Becium homblei, a species previously regarded as characteristic of metalliferous soils, HowardWilliams (1970) showed that it survives competition with the similar B. obovatum not only on metalliferous but also on base-poor soils. The present work has been concerned to discover whether species and ecotypes from the metalliferous areas generally have greater tolerance of metalliferous soils than species and ecotypes from non-metalliferous sites. It is known (for review see Antonovics, Bradshaw & Turner 1971) that some endemic species and ecotypes from metalliferous soils in Europe have evolved specific tolerance of the metals. This is not necessarily the case where, as in Rhodesia, the soils adjacent to metalliferous sites are also infertile, but for other reasons including ready availability of aluminium, manganese and iron. Comparisons of tolerance within and between species were based on the interaction soil x population on yield of plants raised from seed and grown in soil from one or both of two metalliferous areas and in a control soil. Similar methods were used by Kruckeberg (1951), Bradshaw (1952), Walker (1954) and Proctor (1971a, b) but all these workers employed unfertilized soils. In order to eliminate as far as possible effects of differing major nutrient content, all three soils used were fertilized equally with a balanced nutrient solution. Also, the soils were diluted with two parts by weight of sand to reduce effects of differing texture; nutrient applications were made in numerous small portions to avoid exposing the plants to high salt concentrations and differential losses by fixation or denitrification. It was found (Wiltshire 1972a) that fertilization with ammonium and nitrate had different effects on accumulation and distribution of nickel in certain plants on one of the metalliferous soils. Ammonium fertilization acidified and thus increased availability of nickel from this soil. On the other hand, some species grew better with ammonium than with nitrate whether on metalliferous or non-metalliferous soil (Wiltshire 1972b, 1973). * Present address: Tobacco Research Institute, Private Bag, Rustenburg, Transvaal, South Africa.

Nutritive Value of Triticale for Broiler Chick Diets

TRITlCALE is a synthesized hexaphoid species of grain that combines the genomes of Triticum durum and Secale cereale (Sell et al., 1962). The grain was first tested in chick diets by Sell et al. (1962) and results of the test showed that Triticale was inferior compared to wheat for optimum performance. It was suggested that protein quality of the high protein grain was inferior to wheat. The growth response observed after the addition of methionine and lysine to Triticale diets indicated that both of these amino acids were limiting for chick growth in the grain tested.In the development of Triticale for agriculture use, several varieties have been selected. The new varieties are lower in protein, however, the yield per acre is much higher than the original variety tested (Larter, 1968).In view of the potential agricultural value of Triticale as a feed grain, an improved variety of Triticale (produced…

The performance of hybrids between Mediterranean and Northern European parents of cocksfoot (Dactylis glomerataL.) in a mediterranean type environment

Hybrids were produced between seven different parents of Mediterranean origin and two parents of Northern European origin. A special technique of controlled flowering, emasculation, and pollination was used to effect the hybridization. Hybrid plants were grown in undefoliated swards and assessed for cumulative growth, variation in the reproductive phase, tillering, and summer survival. The combining abilities of the parents were estimated for these characters. Hybrids between Mediterranean and Northern European parents were able to respond to summer showers at a time when Mediterranean material was still summer dormant and Northern European material severely affected by dry summer conditions. This out-of-season growth was reflected in the higher yields of the hybrids in the autumn after the main start to the growing season. During midwinter when the Mediterranean material was growing actively the growth of Northern European material ceased and some combinations of Mediterranean and Northern European parents ceased growing. The cessation of growth was attributed to winter dormancy. Plant survival during the summer was 97% for the purely Mediterranean families, 88% for Mediterranean x Northern European families, and 59% for the purely Northern European families. Some of the Mediterranean x Northern European families survived as well as the best Mediterranean families. The potential agricultural value of the Mediterranean x Northern European hybrids and a possible breeding programme with them are discussed.