Archives of Agronomy and Soil Science

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  • ISSN
    1476-3567

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the relationship between the potassium (K) status in the microbial community and the exchangeable K concentration in soils, the effects of K addition on microbial activity were assessed in cultivated Andisols not having received K fertilizer. Potassium limitation was not observed in the microbial community, even in a soil amended with only nitrogen (N) and phosphorus (P) but not K since 1938, though crop plants in this soil showed severe K deficiency symptoms. Furthermore, in a soil amended with NP + compost, microbial activity was limited by K only after limitation of carbon (C) and N. These results suggest that soil microorganisms demand more C and N than K, even in soils with low K availability, and also that the soil microbial community is less susceptible to K deficiency than are crop plants.
    Archives of Agronomy and Soil Science 12/2014; 60(12):1807-1813.
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    ABSTRACT: Despite suggested benefits of hydrochars and biochars, little is known about their effects on root development and root-char interactions. To compare effects of two types of biochar (Pyro and Pyreg) and one hydrochar (HTC) on root growth of spring wheat, two rhizobox experiments were set up where physical contact of roots with chars was prevented using nylon gauze. Rhizoboxes were filled with unamended soil as a control or with three different soil-char mixtures (Pyro, Pyreg and HTC). Shoots and roots were harvested before flowering and at tillering in the first and second experiment, respectively. Chemical soil properties (Nt, K, Ct, pH value) were affected differently by the different chars. Both shoot and root dry matter were influenced by chars. Pyro-char had positive effects on root dry matter in both experiments. At tillering, HTC-char affected root length, root surface and number of root tips negatively. Our findings suggest that nutrients released from chars may affect root morphology of spring wheat. The comparison of different types of chars showed different effects on root growth, shoot growth and soil changes depending on feedstock, production process and the varied amount of chars.
    Archives of Agronomy and Soil Science 11/2014;
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    ABSTRACT: The sustained interest in soil erosion research is an indication of both its importance and the lack of definite solutions that can halt its negative impacts on the environment. This study reviewed the literature on trends, new perspectives, gaps and conflicts in soil erosion studies in the South African context. The suitability of using the relationship between aggregate stability and interrill erodibility as a predictor of the soil susceptibility to erosion was also investigated. This relationship is often used instead of the expensive and time-consuming in situ soil erosion studies and models. There are contradictory reports on its ability to offer quick results on the susceptibility of soil to erosion. However, the reviewed South African and international literature showed that aggregate stability is a widely used physical indicator of soil interrill erodibility. Nevertheless, there is no general agreement on the most suitable aggregate stability indices to use.
    Archives of Agronomy and Soil Science 09/2014;
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    ABSTRACT: This study was attempted to assess the extent of toxicity contributed by Na+ and/or Cl− ions individually, besides their possible additive effects under NaCl using physiological and biochemical parameters. Despite the fact that most annual plants accumulate both Na+ and Cl− under saline conditions and each ion deserves equal considerations, most research has been focused on Na+ toxicity. Consequently, Cl− toxicity mechanisms including its accumulation/exclusion in plants are poorly understood. To address these issues, effects of equimolar (100 mM) concentrations of Na+, Cl− and NaCl (EC ≈ 10 dS m−1) were studied on 15-day-old seedlings of two rice cultivars, Panvel-3 (tolerant) and Sahyadri-3 (sensitive), using in vitro cultures. All three treatments induced substantial reductions in germination rate and plant growth with greater impacts under NaCl than Na+ and Cl− separately. Apparently, salt tolerance of Panvel-3 was due to its ability to exclude Na+ and Cl− from its shoots and maintaining low (<1.0) Na+/K+ ratios. Panvel-3 exhibited better vigour and membrane stability indices coupled with lower reactive oxygen species and lipid peroxidation levels, besides stimulated synthesis of proline, glycine betaine and ascorbic acid. Overall, the magnitude of toxicity was observed in NaCl > Na+ > Cl− manner. Though Cl− was relatively less toxic than its countercation, its effect cannot be totally diminished. Keywords: rice; salinity; ion-specific toxicity; chloride; sodium
    Archives of Agronomy and Soil Science 07/2014;
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    ABSTRACT: Seasonal wetland (dambo) cultivation in smallholder farming areas is important because it improves household food security. However, most farming practices, such as burning of vegetation and conventional tillage in dambo gardens, may reduce soil organic carbon (SOC) and nutrient dynamics. We evaluated the effects of simulated burning, vegetation clearing and clipping, and conventional tillage in dambo gardens on SOC, nutrient contents and biomass production over a 3-year period. The results showed that clearing and clipping of vegetation and conventional tillage reduced SOC, soil nutrient contents and biomass yields, while burning increased SOC and soil nutrient contents. For the 0–10 cm depth, conventional tillage, clearing and clipping resulted in a 37%, 34% and 18% decrease in SOC, respectively, after three seasons, burning resulted in a 25% increase in SOC, while there were no changes in the control after 3 years. For the 0–40 cm depth, the average change in SOC was 32%, 25% and 16% for conventional tillage, clearing and clipping, respectively. Locally and regionally, conventional tillage, clearing and clipping reduce SOC, nutrient contents and biomass production in dambos. Though annual burning increased SOC and nutrient contents in the short term, the long-term effects are uncertain, hence there is a need for long-term studies.
    Archives of Agronomy and Soil Science 02/2014;
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    ABSTRACT: Seasonal wetland (dambo) cultivation in smallholder farming areas is important because it improves household food security. However, most farming practices, such as burning of vegetation and conventional tillage in dambo gardens, may reduce soil organic carbon (SOC) and nutrient dynamics. We evaluated the effects of simulated burning, vegetation clearing and clipping, and conventional tillage in dambo gardens 15 on SOC, nutrient contents and biomass production over a 3-year period. The results showed that clearing and clipping of vegetation and conventional tillage reduced SOC, soil nutrient contents and biomass yields, while burning increased SOC and soil nutrient contents. For the 0–10 cm depth, conventional tillage, clearing and clipping resulted in a 37%, 34% and 18% decrease in SOC, respectively, after three seasons, 20 burning resulted in a 25% increase in SOC, while there were no changes in the control after 3 years. For the 0–40 cm depth, the average change in SOC was 32%, 25% and 16% for conventional tillage, clearing and clipping, respectively. Locally and regionally, conventional tillage, clearing and clipping reduce SOC, nutrient contents and biomass production in dambos. Though annual burning increased SOC and nutrient 25 contents in the short term, the long-term effects are uncertain, hence there is a need for long-term studies.
    Archives of Agronomy and Soil Science 02/2014;
  • Archives of Agronomy and Soil Science 01/2014;
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    ABSTRACT: To reduce climate change risks on maize yield grown in sandy soil, agricultural management practices must be studied. The aim of the study was to determine whether improved water management practices could reduce the vulnerability of maize to drought stress by climate change. Eight fertigation treatments in addition to farmer irrigation (control treatment) were tested. Two climate change scenarios were incorporated in the CropSyst model to assess maize yield responses to variable fertigation regimes under different climate change conditions. The results showed that under current climate, the highest and lowest water productivity (WP) values were obtained when irrigation was applied using 0.8 and 0.6 potential crop evapotranspiration (ETc) with fertigation application in 80% and 60% of application time, respectively. The highest WP under the tested climate change scenarios was obtained when irrigation was applied using 1.2 and 0.8 of ETc with fertigation application in 80% of application time, respectively, in 2009 and 2010 growing seasons. Irrigating maize grown in sandy soil under drip irrigation with an amount of either 1.2 or 0.8 of ETc with fertigation application in 80% of application time are recommended to enhance the WP and reduce maize’s damage caused by extreme climate change.
    Archives of Agronomy and Soil Science 01/2014;
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    ABSTRACT: Different amounts of nitrogen (N) and copper (Cu) in the forms of urea and copper sulfate (CuSO4·5H2O) were applied and their effects on diosgenin production and dry matter yield in fenugreek were investigated under farm cultivation conditions. High-performance liquid chromatography (HPLC) was employed to analyze diosgenin content. Diosgenin contents were measured in 25, 45 and 65 day-old leaves and in leaves at flowering stage and in fruits. The maximum diosgenin content was obtained in 45 day-old leaves. The results showed that simultaneous addition of Cu and N and the level of supply had significant effects on diosgenin production in leaves, fruits and dry matter yield. Simultaneous use of urea (100 kg ha−1) and copper sulfate (30 kg ha−1) increased diosgenin production and dry matter yield in 45 day-old leaves for 7.72 and 1.32 times, respectively, compared to unfertilized control group. But, the use of higher amounts of urea and copper showed a decrease in diosgenin production.
    Archives of Agronomy and Soil Science 10/2013;