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Agriculture, Volume 2, Issue 1 (March 2012) – 6 articles , Pages 1-86

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259 KiB  
Article
Evaluation of Biofertilizers in Irrigated Rice: Effects on Grain Yield at Different Fertilizer Rates
by Niño Paul Meynard Banayo, Pompe C. Sta. Cruz, Edna A. Aguilar, Rodrigo B. Badayos and Stephan M. Haefele
Agriculture 2012, 2(1), 73-86; https://doi.org/10.3390/agriculture2010073 - 14 Mar 2012
Cited by 31 | Viewed by 14011
Abstract
Biofertilizers are becoming increasingly popular in many countries and for many crops, but very few studies on their effect on grain yield have been conducted in rice. Therefore, we evaluated three different biofertilizers (based on Azospirillum, Trichoderma, or unidentified rhizobacteria) in [...] Read more.
Biofertilizers are becoming increasingly popular in many countries and for many crops, but very few studies on their effect on grain yield have been conducted in rice. Therefore, we evaluated three different biofertilizers (based on Azospirillum, Trichoderma, or unidentified rhizobacteria) in the Philippines during four cropping seasons between 2009 and 2011, using four different fertilizer rates (100% of the recommended rate [RR], 50% RR, 25% RR, and no fertilizer as Control). The experiments were conducted under fully irrigated conditions in a typical lowland rice environment. Significant yield increases due to biofertilizer use were observed in all experimental seasons with the exception of the 2008/09 DS. However, the effect on rice grain yield varied between biofertilizers, seasons, and fertilizer treatments. In relative terms, the seasonal yield increase across fertilizer treatments was between 5% and 18% for the best biofertilizer (Azospirillum-based), but went up to 24% in individual treatments. Absolute grain yield increases due to biofertilizer were usually below 0.5 t·ha−1, corresponding to an estimated additional N uptake of less than 7.5 kg N ha−1. The biofertilizer effect on yield did not significantly interact with the inorganic fertilizer rate used but the best effects on grain yield were achieved at low to medium fertilizer rates. Nevertheless, positive effects of the biofertilizers even occurred at grain yields up to 5 t·ha−1. However, the trends in our results seem to indicate that biofertilizers might be most helpful in rainfed environments with limited inorganic fertilizer input. However, for use in these target environments, biofertilizers need to be evaluated under conditions with abiotic stresses typical of such systems such as drought, soil acidity, or low soil fertility. Full article
(This article belongs to the Special Issue Soil Biology and Its Importance in Soil Fertility)
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1251 KiB  
Article
Sorption of Tannin and Related Phenolic Compounds and Effects on Extraction of Soluble-N in Soil Amended with Several Carbon Sources
by Jonathan J. Halvorson, Hero T. Gollany, Ann C. Kennedy, Ann E. Hagerman, Javier M. Gonzalez and Stewart B. Wuest
Agriculture 2012, 2(1), 52-72; https://doi.org/10.3390/agriculture2010052 - 27 Feb 2012
Cited by 12 | Viewed by 11805
Abstract
Some tannins sorb to soil and reduce soluble-N. However, we know little about how they interact with organic amendments in soil. Soil (0–5 cm) from plots, which were amended annually with various carbon substances, was treated with water (control) or solutions containing tannins [...] Read more.
Some tannins sorb to soil and reduce soluble-N. However, we know little about how they interact with organic amendments in soil. Soil (0–5 cm) from plots, which were amended annually with various carbon substances, was treated with water (control) or solutions containing tannins or related phenolic subunits. Treatments included a proanthocyanidin, catechin, tannic acid, β-1,2,3,4,6-penta-O-galloyl-D-glucose (PGG), gallic acid, and methyl gallate. We applied solutions of each of these materials to soil and measured soluble-C and -N in supernatants after application and following extraction with hot water (16 h, 80 °C). Sorption was low for non-tannin phenolics, methyl gallate, gallic acid, and catechin, and unaffected by amendment. Sorption of tannins, proanthocyanidin, tannic acid, and PGG, was higher and greater in plots amended with biosolids or manure. Extraction of soluble-N was not affected by amendment or by catechin, proanthocyanidin, or methyl gallate, but was reduced with PGG, tannic acid and gallic acid. Soil cation exchange capacity increased following treatment with PGG but decreased with gallic acid, irrespective of amendment. Tannins entering soil may thus influence soil organic matter dynamics and nutrient cycling but their impact may be influenced by the composition of soil organic matter. Full article
(This article belongs to the Special Issue Soil Biology and Its Importance in Soil Fertility)
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319 KiB  
Article
Conditions Affecting Shelf-Life of Inoculated Legume Seed
by Rosalind Deaker, Elizabeth Hartley and Greg Gemell
Agriculture 2012, 2(1), 38-51; https://doi.org/10.3390/agriculture2010038 - 06 Feb 2012
Cited by 35 | Viewed by 8567
Abstract
Microbial inoculants are becoming more available as sustainable alternatives to fertilizers and other agrichemicals in broad-acre cropping. However, with the exception of legume inoculants little is understood about effective delivery and survival of the inoculum. Legume inoculants are applied to both seed and [...] Read more.
Microbial inoculants are becoming more available as sustainable alternatives to fertilizers and other agrichemicals in broad-acre cropping. However, with the exception of legume inoculants little is understood about effective delivery and survival of the inoculum. Legume inoculants are applied to both seed and soil but seed inoculation is the most economical technique. Large quantities of pasture seed in Australia are inoculated by commercial seed coating companies, but the long-term survival of seed-applied inoculum is variable and monitoring of viability requires specialist microbiology skills and facilities. The aim of our research was to define optimum storage conditions for survival of rhizobia on legume seed and evaluate water activity as a means of monitoring shelf-life. The relationship between survival and water activity varied according to seed species, inoculum preparation, coating ingredients, initial water activity and time suggesting that storage conditions would need to be defined for each different combination. Although drying seeds after coating significantly reduced viable numbers of rhizobia, survival of rhizobia on dried commercially coated lucerne seed after 11 weeks was less variable than seeds that had not been dried. The highest numbers were maintained when seeds remained dry with water activities of between 0.47 and 0.38. The quality of inoculated seed could be improved by reducing the death rate of inoculum during preparation and providing optimum storage conditions for long-term survival. Full article
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135 KiB  
Article
Differentiation of Blossom Honey and Honeydew Honey from Northwest Spain
by Escuredo Olga, Fernández-González María and Seijo María Carmen
Agriculture 2012, 2(1), 25-37; https://doi.org/10.3390/agriculture2010025 - 20 Jan 2012
Cited by 51 | Viewed by 8910
Abstract
The knowledge of important parameters for honey characterization is an increasing requirement of consumers and the honey industry. In this respect, differentiation between blossom honeys and some honeydew honeys is still an unresolved task. This study includes the results of physicochemical and melissopalynological [...] Read more.
The knowledge of important parameters for honey characterization is an increasing requirement of consumers and the honey industry. In this respect, differentiation between blossom honeys and some honeydew honeys is still an unresolved task. This study includes the results of physicochemical and melissopalynological analysis of 86 honey samples from north-western Spain. The relationship between the microscopic elements in honey, such as Metschnikowia cells and fungal spores from plant pathogens, together with their physicochemical parameters were analysed. A cluster analysis was performed to differentiate blossom honey samples from honeydew samples. Metschnikowia cells and certain fungal spores were found to be good variables to enable differentiation between blossom honeys and honeydew honeys. Full article
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374 KiB  
Article
Effects of Shade on Nitrogen and Phosphorus Acquisition in Cereal-Legume Intercropping Systems
by Meighen Whitehead and Marney E. Isaac
Agriculture 2012, 2(1), 12-24; https://doi.org/10.3390/agriculture2010012 - 19 Jan 2012
Cited by 11 | Viewed by 8567
Abstract
With increasing economic and environmental costs associated with fertilizer use, the need for low-input agroecological systems is on the rise. It is well documented that intercropping legumes can increase the supply of nutrients, through N2-fixation and P mobilization. Concurrently, the integration [...] Read more.
With increasing economic and environmental costs associated with fertilizer use, the need for low-input agroecological systems is on the rise. It is well documented that intercropping legumes can increase the supply of nutrients, through N2-fixation and P mobilization. Concurrently, the integration of trees in the agricultural landscape shows increasing evidence of nutrient inputs through efficient biogeochemical cycles. However, little is known about the effects shade has on legume-crop performance. This research aims to determine whether intercropping of the legumes soybean (Glycine max L. Merr.) and alfalfa (Medicago sativa) with wheat (Triticum turgidum durum) is beneficial for performance, particularly under shady conditions associated with tree-based intercropping. Test species were cultivated in hydroponics with a broad nutrient solution and steady state addition of N for 3 weeks. Individual plants were transferred to rhizoboxes with a 2 mm zone of soil for 16 days under (i) full sun or (ii) shade to mimic light levels at the tree-crop interface. Under monocropping, shading was found to significantly decrease wheat biomass. Intercropping wheat with alfalfa under full sun had no negative effect on growth but did increase wheat P uptake as compared to monocropped wheat. In contrast, intercropping wheat with soybean under full sun decreased wheat biomass, suggesting competition. However, under shade, this competitive effect was mitigated, as wheat exhibited similar biomass and higher N and P shoot concentration when associated with soybean as compared to monocropped wheat under lower light levels. This effect may be attributed to reduced biomass of soybean combined with higher soybean N2-fixation under shade. Legume-based intercrops may increase nutrient supply and growth but these beneficial effects will be dependent on matching species selection to light levels under tree-based intercropping. Full article
(This article belongs to the Special Issue Soil Biology and Its Importance in Soil Fertility)
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175 KiB  
Article
Levels of Sulfur as an Essential Nutrient Element in the Soil-Crop-Food System in Austria
by Manfred Sager
Agriculture 2012, 2(1), 1-11; https://doi.org/10.3390/agriculture2010001 - 12 Jan 2012
Cited by 15 | Viewed by 7330
Abstract
Total sulfur data of various agricultural and food items from the lab of the author, have been compiled to develop an understanding of sulfur levels and ecological cycling in Austria. As sulfur level is not an included factor among the quality criteria of [...] Read more.
Total sulfur data of various agricultural and food items from the lab of the author, have been compiled to develop an understanding of sulfur levels and ecological cycling in Austria. As sulfur level is not an included factor among the quality criteria of soil and fertilizer composition, the database is rather small. Problems in analytical determinations of total sulfur, in particular digestions, are outlined. As a protein component, sulfur is enriched in matrices of animal origin, in particular in egg white. There is substantial excretion from animals and man via urine. Organic fertilizers (manures, composts) might contribute significantly to the sulfur budget of soils, which is important for organic farming of crops with high sulfur needs. For soils, drainage is a main route of loss of soluble sulfate, thus pot experiments may yield unrealistic sulfur budgets. Full article
(This article belongs to the Special Issue Soil Biology and Its Importance in Soil Fertility)
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