Potassium Uptake from the Subsoil by Green Manure Crops

Witter, Ernst; Johansson, Göran

doi:10.1080/01448765.2001.9754917

Cited by 42 publications

(24 citation statements)

References 14 publications

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“…the lowest contents of available K are connected with the negative balance in the first two years of the rotation, with minimum content of 88 mg K/kg in the second year. Because forage crops take up a substantial amount of K from the subsoil (41-67%, Witter and Johansson 2001), the decrease of available K is not as steep as can be expected from the K balance.…”

Section: Methodsmentioning

confidence: 96%

Interannual dynamics of available potassium in a long-term fertilization experiment

Madaras¹,

Lipavský²

2009

PLANT SOIL ENVIRON

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Dynamics of the plant-available potassium (K) has been studied in polyfactorial long-term fertilization experiments since 1980. The fertilization scheme includes 10 combinations of K muriate and farmyard manure application rates (annually 0-230 kg K/ha). at medium treatment (annually 153 kg K/ha), the K balance within an 8-year crop rotation reflected crop specific K application rates with positive annual balances in years of growing silage maize and sugar beet (high K input), and negative in two years of growing alfalfa. available K clearly corresponded to the dynamics of the K balance, with statistically significant fluctuations from 88 to 149 mg K/kg within one crop rotation cycle. Periodic fluctuations of available K induced by crop rotation were observed also in non-fertilized treatments. The variability of available K contents was influenced primarily by crop plants and experimental unexplained factors; interannual weather fluctuations and field differences were of low significance. in the paper, the importance of interannual K dynamics for the construction of correct long-term time trends is shown and discussed.

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Section: Methodsmentioning

confidence: 96%

Interannual dynamics of available potassium in a long-term fertilization experiment

Madaras¹,

Lipavský²

2009

PLANT SOIL ENVIRON

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“…The importance of subsoil K is clearly apparent from K/Rb isotope dilution studies demonstrating that the extent of uptake is directly proportional to rooting depth [99][100][101] . This uptake is largely concentrated in the vegetative biomass 33,102 , and enriches the surface soil when inorganic K leaches from plant shoots or residues 8,9,81,[102][103][104][105][106] (see supplemental references [35][36][37][38][39][40][41][42][43][44][45] for the online version of the paper).…”

Section: Evaluation Of Soil Potassium Testingmentioning

confidence: 99%

The potassium paradox: Implications for soil fertility, crop production and human health

Khan

Mulvaney

Ellsworth

2013

Renew. Agric. Food Syst.

100

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Intensive fertilizer usage of KCl has been inculcated as a prerequisite for maximizing crop yield and quality, and relies on a soil test for exchangeable K in the plow layer to ensure that soil productivity will not be limited by nutrient depletion. The interpretive value of this soil test was rigorously evaluated by: (1) field sampling to quantify biweekly changes and seasonal trends, (2) characterizing the variability induced by air drying and the dynamic nature of soil K reserves and (3) calculating the K balance in numerous cropping experiments. These evaluations leave no alternative but to question the practical utility of soil K testing because test values cannot account for the highly dynamic interchange between exchangeable and non-exchangeable K, exhibit serious temporal instability with or without air drying and do not differentiate soil K buildup from depletion. The need for routine K fertilization should also be questioned, considering the magnitude and inorganic occurrence of profile reserves, the recycling of K in crop residues and the preferential nature of K uptake. An extensive survey of more than 2100 yield response trials confirmed that KCl fertilization is unlikely to increase crop yield. Contrary to the inculcated perception of KCl as a qualitative commodity, more than 1400 field trials predominately documented a detrimental effect of this fertilizer on the quality of major food, feed and fiber crops, with serious implications for soil productivity and human health.

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“…Other studies have shown that subsoil K uptake in spring cereals can account for up to 50 % of total K uptake (Kuhlmann 1990) and up to 55 % in ryegrass and clover mixtures (Witter and Johansson 2001). Hence, it is possible that, due to the deeper root systems generally found in multiple-crop systems, such subsoil K resources can be utilised more effectively, when crops are subjected to interspecific competition.…”

Section: Potassiummentioning

confidence: 99%