Potassium Supplying Capacity of Diverse Soils and K-Use Efficiency of Maize in South Asia

Abstract

Increased nutrient withdrawal by rapidly expanding intensive cropping systems, in combination with imbalanced fertilization, is leading to potassium (K) depletion from agricultural soils in Asia. There is an urgent need to better understand the soil K-supplying capacity and K-use efficiency of crops to address this issue. Maize is increasingly being grown in rice-based systems in South Asia, particularly in Bangladesh and North East India. The high nutrient extraction, especially K, however, causes concerns for the sustainability of maize production systems in the region. The present study was designed to estimate, through a plant-based method, the magnitude, and variation in K-supplying capacity of a range of soils from the maize-growing areas and the K-use efficiency of maize in Bangladesh. Eighteen diverse soils were collected from several upazillas (or sub-districts) under 11 agro-ecological zones to examine their K-supplying capacity from the soil reserves and from K fertilization (100 mg K kg−1 soil) for successive seven maize crops grown up to V10–V12 in pots inside a net house. A validation field experiment was conducted with five levels of K (0, 40, 80, 120 and 160 kg ha−1) and two fertilizer recommendations based on “Nutrient Expert for Maize-NEM” and “Maize Crop Manager-MCM” decision support tools (DSSs) in 12 farmers’ fields in Rangpur, Rajshahi and Comilla districts in Bangladesh. Grain yield and yield attributes of maize responded significantly (p < 0.001) to K fertilizer, with grain yield increase from 18 to 79% over control in all locations. Total K uptake by plants not receiving K fertilizer, considered as potential K-supplying capacity of the soil in the pot experiment, followed the order: Modhukhali > Mithapukur > Rangpur Sadar > Dinajpur Sadar > Jhinaidah Sadar > Gangachara > Binerpota > Tarash > Gopalpur > Daudkandi > Paba > Modhupur > Nawabganj Sadar > Shibganj > Birganj > Godagari > Barura > Durgapur. Likewise, in the validation field experiment, the K-supplying capacity of soils was 83.5, 60.5 and 57.2 kg ha−1 in Rangpur, Rajshahi, and Comilla, respectively. Further, the order of K-supplying capacity for three sites was similar to the results from pot study confirming the applicability of results to other soils and maize-growing areas in Bangladesh and similar soils and areas across South Asia. Based on the results from pot and field experiments, we conclude that the site-specific K management using the fertilizer DSSs can be the better and more efficient K management strategy for maize.

Potassium Bioavailability in a Tropical Kaolinitic Soil

“…However, in this study, except for unfertilized pots, diagnostic leaf analysis did not reveal insufficient levels of any nutrient (data not shown) that could explain the decrease in dry matter production. Despite plant uptake of K from fractions that are less soluble than exchangeable K, uptake and removal of soil K over successive crop cycles can eventually lead to a decrease in K and dry matter production [43][44][45]. The use of ruzigrass to deplete soil exchangeable K was very effective (Figure 2A), as observed in previous studies [34].…”

Co-benefits of nutrient management tailored to smallholder agriculture

“…Studies included were peer reviewed journal publications, book chapters, or technical reports that explicitly compared SSNM and FFP in the same fields. Consequently, studies that compared SSNM to other treatments such as a no input control, blanket fertilizer recommendation, or soil test based recommendations were not included ( Dogbe et al, 2015 ; Islam et al, 2018 ; Saito et al, 2019 ; Rurinda et al, 2020 ). Most of the studies reported in this study were conducted on-farm, and only five were conducted on-station.…”

Effects of Straw-Return Method for the Maize–Rice Rotation System on Soil Properties and Crop Yields

“…Consistent with Zhao et al [58], we found that soil pH increased under M i R i and M m R i treatments (Table 2), which indicated increases in soil K + fixation and reductions in K + loss by leaching. Increased pH generates new charges in the surface of the soil constant potential and increases the amount of K + adsorption, so K + more easily replaces Ca 2+ instead of replacing H + and Al 3+ [59,60]. Straw return may help effectively regulate soil pH within an appropriate range for balancing soil nutrient fixation and recharge [29].…”