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Rosolem, Ciro Antônio; Nakagawa, João

doi:10.1023/a:1017555023168

Cited by 12 publications

(1 citation statement)

References 6 publications

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“…In a study conducted over three years in a Oxisol with 120 g kg -1 of clay in São Manoel (SP), Rosolem and Nakagawa (2001) reported an increase in the rate of leaching of K in the profile when doses above 80 kg ha -1 of K 2 O per year, regardless of the fertilizer application method. This movement of K in the soil profile to depths below those explored by the roots, especially in the higher doses, indicates that the losses of K by leaching can be significant in medium textured soils.…”

Section: Application Seasons Of Potassium Accumulation Of K 2 O In Thmentioning

confidence: 99%

Doses and Application Seasons of Potassium in the Soybean-Corn Succession in Soil With Improved Fertility in the Southwest of Goiás

Xavier¹,

Carneiro²,

Guimarães³

et al. 2019

JAS

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Soils with improved fertility indicate opportunities for more rational use of fertilizers. The objective of this study was to evaluate the management of potassium fertilization in the succession of soybean-corn in soil with improved fertility, in the southwestern region of the state, Goiás. The experiment was set in 5×3 factorial scheme, arranged in randomized blocks with four repetitions. The treatments consisted of the combination of potassium doses (0, 40, 80, 120 and 160 kg ha-1 of K2O) and seasons of application (100% of the dose in pre-planting, 100% of the dose in coverage and in installments with 50% of the dose in pre-planting + 50% in coverage). The best performance of soybean, considering grain yield, was obtained with the parceled application of 80 kg ha-1 of K2O, with production of 3.6 Mg ha-1. The highest corn production was obtained with the anticipated application of 160 kg ha-1 of K2O in soybean. In the management of potassium fertilization in improved fertility soil in the soybean-corn succession, the parceled application of 120 kg ha-1 of K2O kept the available K reserve in the soil constant when compared to its initial content.

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Section: Application Seasons Of Potassium Accumulation Of K 2 O In Thmentioning

confidence: 99%

Doses and Application Seasons of Potassium in the Soybean-Corn Succession in Soil With Improved Fertility in the Southwest of Goiás

Xavier¹,

Carneiro²,

Guimarães³

et al. 2019

JAS

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Potassium management in tea plantations: Its uptake by field plants, status in soils, and efficacy on yields and quality of teas in China

Ruan

Shi

2013

Z. Pflanzenernähr. Bodenk.

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Tea is one of the major cash crops in the tropical and subtropical areas of China. Insufficient potassium (K) supply is an important limiting factor to the productivity as the soils are highly leached and strongly acidic. However, information about effects of K fertilization and application techniques is very limited. This manuscript summarizes results of field experiments investigating K uptake, soil K status, effects and methods of K fertilization in China during the past two decades. The K stocks and uptake were investigated by soil sampling in plantations aged 1, 2, 3, 5, and 10 years. There was no harvest of young shoots, and most K was assigned to frame growth accounting for 59%-61% of the total uptake in the aboveground plant parts of young plantations aged 1-3 years. In plantations (≥ 5 years) such assignment to frame growth became relatively small (7.6%-11.9%) and a major proportion was assigned to young shoots accounting for up to 78% of the total. Analysis of 3396 soil samples taken in 2009-2010 from 54 counties of 16 main tea-producing provinces showed that the exchangeable K (extracted by Mehlich III) in soils averaged 81 mg kg -1 and in about 74% samples were below critical deficient level (100 mg kg -1 ). The low activity ratio at equilibrium (AR k e ) and nonspecific absorbed-K (DK 0 ) values of quantityintensity (Q/I) curves also indicated low status of labile K pools of tea soils. Field experiments at 16 of total 18 sites with black, green, and oolong teas during 1992-2002 showed a significant increase of yield after K application either as potassium sulfate (K 2 SO 4 ) or potassium chloride (KCl) despite of the largely different initial soil exchangeable K contents, plucking standards, and yield levels among the tea types. The agronomical efficiency of K fertilizers was averaged at 8.8 kg fresh shoots or 1.71 kg tea per kg K fertilizer. The quality of harvested shoots was improved by K-fertilizer application as revealed by increased concentrations of free amino acids, water-extractable dry matter, and total polyphenols. There was little difference in the effects of K as K 2 SO 4 and KCl on yield and quality. Field experiments at six sites evaluating variable K amounts demonstrated that the optimal K doses ranged from 124 to 160 kg K ha -1 y -1 for both K 2 SO 4 and KCl and were little affected by initial soil K contents, tea types, and the yield levels. No privilege of K applications split into three times in tea seasons was observed concerning the risk of leaching in the soils of low cation-exchange capacity and abundant rainfall in the production areas. A single K application as base fertilizer in autumn had similar or better effect. The present studies showed low soil labile K pools, incapable to meet plant K demand for quality tea production, highlighting the importance of K-fertilizer application.Key words: agronomical efficiency / soil K availability / potassium fertilizer / plantations of different ages / quantity-intensity curve

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Nutrient release from K-feldspar ore altered in hydrothermal conditions

Ciceri

Allanore

2019

Chem. Pap.

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The development of potash materials from local K-bearing resources such as aluminosilicate minerals is desirable to overcome reliance on imported fertilizers in tropical countries. However, the nutrient release from such materials follows a time-dependent profile that is not well-understood and that is significantly different if probed at agronomic or geological timescales. This work investigates the nutrient release from a calcium-aluminumsilicate-hydrate (C-A-S-H) material obtained via hydrothermal alteration of K-feldspar ore and CaO. The C-A-S-H hydrothermal material is subjected to sequential leaching cycles with diluted HNO3 (initial pH=5), renewing the leaching solution at every cycle. X-Ray Powder Diffraction (XRD) is used to monitor changes in the material mineralogy as the leaching progresses, showing a relative increase of calcite (up to 7 wt%) and amorphous phase (up to 23 wt%). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) of the leachates is used to monitor the release of K, Ca, Si and Al, and shows that the material releases K nutrient at every leaching cycle. The pH of the leachates shows that as the content of calcite in the material increases a buffering capacity at pH≈9.6 is developed by the material. The mineralogy, nutrient release, and pH results presented in this study suggest a potential application of the material as a slow release fertilizer when compared to KCl. Experimental results also imply that kinetic parameters rather than solubility are more suited to describe the fertilizer value of silicate materials.

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Cited by 12 publications

References 6 publications

Doses and Application Seasons of Potassium in the Soybean-Corn Succession in Soil With Improved Fertility in the Southwest of Goiás

Doses and Application Seasons of Potassium in the Soybean-Corn Succession in Soil With Improved Fertility in the Southwest of Goiás

Potassium management in tea plantations: Its uptake by field plants, status in soils, and efficacy on yields and quality of teas in China

Nutrient release from K-feldspar ore altered in hydrothermal conditions

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