An evaluation of the availability of potassium in crop residues

Grimes, D. W.

doi:10.31274/rtd-180816-2198

Cited by 1 publication

(1 citation statement)

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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). 3 Parentheses indicate digital uncertainty in estimating data reported in figures.…”

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.

103

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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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