Temporal variation of soil nutrients under the influence of different organic amendments

Maintenance of tropical soil quality for crop production without damaging the environment is a challenge and thus the development of an efficient nutrient-management technique is important. Soil amendment by organic manures has been widely accepted as an efficient nutrient-management technique in tropical agriculture. In this study, a long-term laboratory experiment was conducted to investigate the influence of organic manures of different sources (e.g. cattle manure, poultry manure, vermicompost and oil cakes) on changes in pH, electrical conductivity, organic C and nutrient content (mineral N, available phosphorous and potassium) in tropical alluvial soil. Applications of organic amendments in this study indicated considerable changes in the basic soil physico-chemical properties and different nutrient levels. Soil pH declined slightly, whereas organic C and all the other nutrients increased distinctly, due to the application of organic manures. Thus, the magnitude of changes in the soil properties was dependent on the nature of the organic manure.     

DIFFERENCES IN ACQUISITION OF ORGANIC NITROGEN IN SOILS BETWEEN BOK CHOY AND TOMATO

Seedlings of bok choy and tomato were grown in soils with different nitrogen (N) sources [no N (?N), ammonium sulfate (AS), and cattle farmyard manure (CM)]. Comparison between soils treated with ?N and CM indicated that the growth and N accumulation in bok choy were significantly enhanced by CM treatment, whereas no difference was found in tomato. In the rhizosphere soils, the highest protease activity was detected in CM treatment irrespective of species. Correlation analysis between rhizospheric protease activity and total N accumulation of plant treated with –N and CM showed a significant positive correlation only for bok choy. The determination of amino acid absorption rate in excised roots indicated that glycine was taken up at a significantly higher rate in bok choy than tomato. This study suggested that at least two possible factors affected the acquisition of organic N: rhizospheric protease activity and ability to absorb amino acids in roots.     

The effect of nickel supply on bulb yield,urease and glutamine synthetase activity and concentrations of urea,amino acids and nitrogen of urea-fed onion plants

The role of nickel (Ni) on urea metabolism of certain plants has been documented, but little is known regarding the growth and physiological response of onion to Ni nutrition, particularly when urea is used as nitrogen source. In this research study, we investigated the effects of Ni on urea metabolism and growth of two onion cultivars (Allium cepa L., cvs. Dorrcheh and Cebolla Valenciana) supplied with urea as nitrogen source. Three levels of Ni (0, 25, and 50 µM) were used in the form of NiCl₂ or Ni-histidine [Ni(His)₂] complex. Addition of Ni positively affected nitrogen metabolism in onion plants fed with urea and thus was correlated with increase of the bulb yield. Regardless of the plant cultivar and the applied Ni source [NiCl₂ or Ni(His)₂ complex], an increase in urease activity and reduction in bulb urea concentration was observed by Ni nutrition. An increase in hydrolysis of urea and production of NH₄⁺ in the presence of Ni was correlated with higher concentration of the total amino acids (AAs) and nitrogen in onion bulbs. The efficiency of Ni(His)₂ complex in improving Ni uptake and increasing activity of urease and glutamine synthetase, two enzymes involved in urea metabolism, was in general greater than NiCl₂. Accordingly, higher concentration of AAs was measured in the onion plants supplied with Ni(His)₂ complex than those supplied with NiCl₂.     

Effect of phosphorus addition on onion plants grown in 13 soils of varying degree of weathering

Phosphorus (P) phytoavailability decreases with soil weathering, however P dynamics in high-P soils with relatively narrow differences in weathering and further addition of P is not known. In the present study, P dynamics and availability in soils varying in their chemical properties and P availability were examined. Onion plants were grown in 13 high-P soils at two P levels [Ρ0 and Ρ1]. Extractable P was assessed with Olsen, Mechlich-3, ammonium oxalate, and water soluble methods, as well as plant tissues P content and morphological features. Despite the initial high P content, all the measured parameters, including soil P, plant morphology, and P content, further increased at P1 compared to P0. Moreover, water soluble P, bulb weight, and plant P content exhibited greater differences between P0 and P1 in Alfisols. In conclusion, for high-P soils, P application could increase traits, such as onion bulb weight, especially for soils with higher weathering.     

洋葱氮磷钾肥配施效应模型构建及其推荐用量研究

为研究安丘市洋葱对氮、磷、钾肥的肥效反应和适宜用量,采用\"3414\"试验方案设计,研究肥料配施对洋葱产量的影响及最高产量和最佳经济效益时氮、磷、钾肥的推荐施用量。结果表明,氮、磷、钾肥配施可显著提高洋葱产量,最大增产率达103.99%。氮、磷、钾肥间存在明显的交互作用,各因素对洋葱产量的影响顺序为钾氮磷,高量处理均表现为产量减少。经回归模型的拟合表明,本试验不适合用三元二次肥效模型;二元二次和一元二次肥效模型可较好地表达施肥量与产量间的关系。通过肥效模型计算可知,洋葱达到最高产量时氮(N)、磷(P2O5)、钾(K2O)的施入量分别为1 443.4、2 359.4、1 632.0 kg/hm2,达到最佳经济产量时氮(N)、磷(P2O5)、钾(K2O)的施入量分别为1 343.2、1 852.3、1 400.2 kg/hm2。     

Biofortification of onion bulb with selenium at different levels of sulfate

In this research experiment, two commercial onion cultivars (Allium cepa L., cvs. Dorrcheh and Cebolla Valenciana) were grown in sand culture and exposed to two levels of selenium (Se) (0 and 25?µM) and two levels of sulfate (1 and 3?mM). According to the results obtained, addition of 25?µM Se in combination with 3?mM sulfate was not only effective in significant increase of onion bulb yield, but it significantly increased Se concentration of bulb. By considering the average consumption of onion in central Iran, the daily intake of Se via consumption of Se-biofortified onion is estimated to be 68.4–77.2?µg in spring and summer and 72.6–117.1?µg in fall and winter. These amounts of daily intakes of Se is higher than the sufficient levels of Se recommended by world health organization (WHO) but less than the maximum tolerable level of Se (400?µg Se per day) for human.     

On the origin and distribution of normal cytoplasm of onion

Seventy populations of bulb onion (Allium cepa) from the Middle East, Central Asia, and Indian subcontinent introduced into the United States National Plant Germplasm System before 1964 were evaluated for the presence of normal (N) male-fertile and male-sterile (S) cytoplasms using three polymorphisms in the chloroplast genome. One accession acquired in 1948 from Turkey possessed only S cytoplasm. Fifty accessions possessed only N cytoplasm. Nineteen accessions possessed both N and S cytoplasm, of which S predominated in two accessions. The prevalence of N cytoplasm among populations originating from the Central Asian center of origin supports it as the wild type cytoplasm of onion. One accession of A. vavilovii recently collected in Turkmenistan was identical to N cytoplasmic onion for all of 42 previously characterized polymorphisms in the chloroplast genome, at all sites for 12 restriction enzymes in the nuclear 45s ribosomal DNA, and for 68 of 72 mitochondrial probe-enzyme combinations. Polymorphisms between this accession of A. vavilovii and three N cytoplasmic onions were detected only with cytochrome oxidase subunit 1 and four restriction enzymes. The cytoplasm of A. vavilovii is closely related to N cytoplasm and this species may be the progenitor of bulb onion.     

DETERMINING THE ZINC REQUIREMENT OF ONION BY SEED ANALYSIS

Our study analyzed the effect of foliar tissues and seed tissue for determining the micronutrient status of a crop. Zinc (Zn) requirements of onion (Allium cepa L.) leaves and seeds were estimated from yield response curves based on field experiment conducted on a Zn-deficient calcareous soil. Three onion cultivars, i.e., ‘Swat-1’, ‘Phulkara’, and ‘Sariab Red’ were grown by applying 0, 2, 4, 8, and 16 kg Zn ha^?1. Zinc application significantly increased seed yield of all the three cultivars of onion. The order of seed yield response to Zn fertilization was: ‘Swat-1’ < ‘Phulkara’ < ‘Sariab Red’. Fertilizer Zn requirement for near-maximum seed yield was 2 kg Zn ha^?1. Zinc concentration in mature onion seed also appeared to be a good indicator of soil Zn availability status. Critical Zn concentration in seed was 18 mg Zn kg^?1, and in matured leaves was 21 mg kg^?1.     

除氨菌系对牛粪堆肥氮素转化的影响

为了减轻牛粪堆肥过程中NH3释放对环境的污染及氮素损失,在牛粪堆肥时添加除氨菌系,研究其对氮素形态转化的影响。加除氨菌系处理的NH4+-N、NH3较对照分别降低20.47%和61.21%,全氮、NO3--N较对照分别提高11.63%和65.01%,酸解有机氮、氨基酸态氮、酰胺态氮和氨基糖态氮含量分别提高12.42%、11.26%、16.92%和19.51%。表明除氨菌系在牛粪堆肥过程中,能够固定NH4+-N向有机氮各组分转化,减少NH3挥发,具有较好的保氮作用。     

Nitrogen-fixing microorganisms in paddy soils (Part 1) Characteristics of the nitrogen fixation in paddy soils

In most paddy soils, as is already well-known, the crop yield goes on decreasing just for the first few years and then stabilizes at a comparatively high level with no supply of fertilizer or manure.     

Developing and Evaluation of Ecofriendly Fertilizer from Poultry Waste to Enhance Pulse Production in Alfisols of Semi-arid Tropics

Poultry manure (PM) has long been recognized the most desirable organic fertilizer. It improves soil fertility by adding both major and essential nutrients, as well as soil organic matter, which improves moisture and nutrient retention. The present study investigates the effectiveness of different levels of applied poultry-manure compost (PMC) and phospho-poultry-manure compost (PPMC) on the growth and yield of blackgram (Vigna mungo L). A field experiment was conducted to assess the nutrient-supplying capacity and soil health improvement potential of PMC and PPMC at 3.12, 6.25, 9.37, and 12.5 t/ha and to find the optimum dose of PMC as an organic fertilizer to maximize the pulse production in Alfisols of semi-arid tropics. Application of PPMC at 12.5 and 9.37 t ha^?1 increased the seed yield 105% and 102% more than the no-manure plot. Application of PMC at 12.5 t ha^?1 recorded 80% yield increment than no manure applied and the yield difference of PPMC was 20 to 25% greater than PMC alone. Application of PPMC at 12.5 and 9.37 t ha^?1 resulted in desirable soil physical and chemical properties especially 85 and 70% soil-available P improvement and significant role in increasing yield of blackgram. Application of PPMC at 9.37 t ha^?1 was found to be economically viable to the farmers in terms of improvement in soil properties and crop yield.