Exploring the potential of phyllosilicate minerals as potassium fertilizers using sodium tetraphenylboron and intensive cropping with perennial ryegrass

Abstract

In response to addressing potassium (K) deficiency in soil and decreasing agricultural production costs, the potential of K-bearing phyllosilicate minerals that can be directly used as an alternative K source has been investigated using sodium tetraphenylboron (NaTPB) extraction and an intensive cropping experiment. The results showed that the critical value of K-release rate and leaf K concentration was 3.30 g kg−1 h−1 and 30.64 g (kg dry matter)−1, respectively under the experimental conditions. According to this critical value, the maximum amount of released K that could be utilized by a plant with no K deficiency symptoms was from biotite (27.80 g kg−1) and vermiculite (5.58 g kg−1), followed by illite, smectite and muscovite with 2.76, 0.88 and 0.49 g kg−1, respectively. Ryegrass grown on phlogopite showed K deficiency symptoms during the overall growth period. It is concluded that biotite and vermiculite can be directly applied as a promising and sustainable alternative to the use of classical K fertilizers, illite can be utilized in combination with soluble K fertilizers, whereas muscovite, phlogopite and smectite may not be suitable for plant growth. Further field experiments are needed to assess the use of these phyllosilicate minerals as sources of K fertilizer.

Soil Reserves of Potassium: Release and Availability to Lolium perenne in Relation to Clay Minerals in Six Cropland Soils from Eastern China

“…The data on the release of K from soil reserves for all soils were fitted to the power function (Table ). The release from all soils was rapid initially but slowed down later, as observed earlier by others as well (Hosseinpur & Motaghian, ; Sarkar et al ., ; Li et al ., ). The data for two segments (0–2 and 4–144 h) fitted the power function well ( R 2 0–2h = 0·779–0·976; mean, 0·901; R 2 4–144h = 0·833–0·989; mean, 0·933).…”

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

“…The bioavailability of K in soils was ranked in terms of the potential capacity of a soil to sustain plant growth with no additional K fertilizer, and was mainly related to plant growth and the release characteristics of K in soils7263335. Table 3 shows the available grading criterion of soil K with the parameters we propose.…”

“…There were two K treatments: (i) no K fertilizer was applied throughout the experimental period; and (ii) potassium sulfate (200 mg K kg −1 soil) was applied as a K fertilizer. To ensure that the general nutrient supply did not limit plant growth, basal nutrients were applied initially and after each harvest72635. The first basal application was given before initiation of the experiment and soils were allowed to equilibrate for 1 week at field capacity; they were watered with deionized water every 1–2 days to maintain soil moisture close to 80% of field capacity throughout the pot culture period.…”

“…Plant biomass yield (BY) and K concentration (Kc) were used to determine plant K absorption274041. Cumulative K uptake was the summation of plant uptake for each crop harvest26.…”

“…Some researchers have described the release of K by equations containing three simultaneous rate terms212223, which can be divided graphically into simultaneous rates of K release from the surface of the soil complex, the weathered periphery, and the micaceous matrix. However, several researchers have defined K release by two simultaneous reactions, relating to the release of external and lattice K, respectively1118242526. Thus, the question arises as to whether the release rate of K in the soil correlates with the grading of plant-available K in that same soil.…”