Assessment of the Potassium Supplying Capacity of Coastal Entisols and Inceptisols under Intensive Cropping and Fertilization

ABSTRACT

The coastal soils are characterized by unpredictable and often abysmal pattern of nutrient release and availability. In order to have an impeccable outlook of this unpredictability and in the dearth of appropriate literatures, the current study has been formulated in some eastern Indian coastal Entisols and Inceptisols. Greenhouse potassium (K)-exhaustion experiments in pots were conducted using four coastal soils to assess the depletion of available and non-exchangeable K through intensive cropping with two years of rotation (paddy–greengram–sunflower) under no-fertilizer (control) and varying fertilization (NP, K, and NPK). The initial water-soluble, available, non-exchangeable, and total K content of soils varied from 10.2–43.1, 68.8–257.5, 534–982, and 11,800–23,000 mg kg⁻¹, respectively. Results showed that crop K uptake followed NPK>K> NP>control, which emphasizes the need for integrated NPK application. The depletion of soil-available and non-exchangeable K to crop uptake was 8.1–21.3%, 8.2–19.3%, 37.5–48.2%, and 33.8–43.1% and 78.7–91.9%, 80.7–91.8%, 51.8–62.5%, and 56.9–66.2% in control, NP, K, and NPK treatment, respectively. The mining of soil K to crop nutrition was higher in Inceptisol with lower amounts of available and non-exchangeable K reserves than in newer Entisols enriched with soil K reserves. The results further exemplify that overdependence on reserve K for crop uptake can be detrimental, and thus for sustaining intensive cultivation, particularly in high-rainfall areas, the unpredictable K release should rather be nullified by integrated NPK application. Therefore, precise K-management strategy for sustainable crop yield, regular monitoring, and soil test-based K fertilization must be ensured against the downward spiraling of K fertility of coastal soils.

KEYWORDS:

• Non-exchangeable K
• K supply
• coastal soil
• K exhaustion
• eastern India

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work.