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A new grading system for plant-available potassium using exhaustive cropping techniques combined with chemical analyses of soils

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ABSTRACT

A new grading system for plant-available potassium (K) in soils based on K release rate from soils and plant growth indices was established. In the study, fourteen different agricultural soils from the southern subtropical to the northern temperate zones in China were analyzed by both chemical extraction methods and exhaustive cropping techniques. Based on the change trends in plant growth indices, relative biomass yields of 70% and 50%, K-deficient coefficients of 35 and 22 under conventional exhaustive experiments, and tissue K concentrations of 40 g kg−1 and 15 g kg−1 under intensive exhaustive experiments were obtained as critical values that represent different change trends. In addition, the extraction method using 0.2 mol L−1 sodium tetraphenylboron (NaTPB) suggested soil K release rates of 12 mg kg−1 min−1 and 0.4 mg kg−1 min−1 as turning points that illustrated three different release trends. Thus, plant-available K in soils was classified into three categories: high available K, medium available K and low available K, and grading criteria and measurement methods were also proposed. This work has increased our understanding of soil K bioavailability and has direct application in terms of routine assessment of agriculture soils.

No MeSH data available.


Relation between relative biomass yield and K-deficient coefficient of ryegrass under conventional exhaustive experiment.The right-angled lines in the figures reflect the inflexion points of K-deficient coefficient of ryegrass based on the critical values of relative biomass yield.
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f2: Relation between relative biomass yield and K-deficient coefficient of ryegrass under conventional exhaustive experiment.The right-angled lines in the figures reflect the inflexion points of K-deficient coefficient of ryegrass based on the critical values of relative biomass yield.

Mentions: We established the relation between RBY and the K-deficient coefficient of ryegrass under a conventional exhaustive experiment (Fig. 2). A statistically significant correlation (p < 0.01) showed that RBY decreased with a decreasing K-deficient coefficient of ryegrass, indicating that K deficiency was the most important growth-limiting factor in our exhaustive experiment. A logarithm equation was found to best describe the relation between RBY and the K-deficient coefficient of ryegrass (R2 = 0.891) (Fig. 2). The critical values of the RBY (70% and 50%) were used to grade the K status in soils to judge available K supplication to plant growth. According to these parameters, the ryegrass K-deficient coefficients of 35 and 22 were obtained as inflexion points in the current study.


A new grading system for plant-available potassium using exhaustive cropping techniques combined with chemical analyses of soils
Relation between relative biomass yield and K-deficient coefficient of ryegrass under conventional exhaustive experiment.The right-angled lines in the figures reflect the inflexion points of K-deficient coefficient of ryegrass based on the critical values of relative biomass yield.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120352&req=5

f2: Relation between relative biomass yield and K-deficient coefficient of ryegrass under conventional exhaustive experiment.The right-angled lines in the figures reflect the inflexion points of K-deficient coefficient of ryegrass based on the critical values of relative biomass yield.
Mentions: We established the relation between RBY and the K-deficient coefficient of ryegrass under a conventional exhaustive experiment (Fig. 2). A statistically significant correlation (p < 0.01) showed that RBY decreased with a decreasing K-deficient coefficient of ryegrass, indicating that K deficiency was the most important growth-limiting factor in our exhaustive experiment. A logarithm equation was found to best describe the relation between RBY and the K-deficient coefficient of ryegrass (R2 = 0.891) (Fig. 2). The critical values of the RBY (70% and 50%) were used to grade the K status in soils to judge available K supplication to plant growth. According to these parameters, the ryegrass K-deficient coefficients of 35 and 22 were obtained as inflexion points in the current study.

View Article: PubMed Central - PubMed

ABSTRACT

A new grading system for plant-available potassium (K) in soils based on K release rate from soils and plant growth indices was established. In the study, fourteen different agricultural soils from the southern subtropical to the northern temperate zones in China were analyzed by both chemical extraction methods and exhaustive cropping techniques. Based on the change trends in plant growth indices, relative biomass yields of 70% and 50%, K-deficient coefficients of 35 and 22 under conventional exhaustive experiments, and tissue K concentrations of 40&thinsp;g&thinsp;kg&minus;1 and 15&thinsp;g&thinsp;kg&minus;1 under intensive exhaustive experiments were obtained as critical values that represent different change trends. In addition, the extraction method using 0.2&thinsp;mol&thinsp;L&minus;1 sodium tetraphenylboron (NaTPB) suggested soil K release rates of 12&thinsp;mg&thinsp;kg&minus;1 min&minus;1 and 0.4&thinsp;mg&thinsp;kg&minus;1 min&minus;1 as turning points that illustrated three different release trends. Thus, plant-available K in soils was classified into three categories: high available K, medium available K and low available K, and grading criteria and measurement methods were also proposed. This work has increased our understanding of soil K bioavailability and has direct application in terms of routine assessment of agriculture soils.

No MeSH data available.