Predicting the response of soil potassium to broccoli (Brassica oleracea var. italica) in a Gangetic Inceptisol of West Bengal, India through suitable chemical extractants

Abstract

Finding a suitable method for estimating soil and crop specific potassium (K) bioavailability under variable range of soil fertility has been a mighty challenge. To undermine this, a field experiment was conducted under varying levels of fertilizer application on pre-established fertility gradient strips in the Indo-Gangetic plains of West Bengal, India for predicting crop response and to assess the K availability in winter growing broccoli by employing six acclaimed chemical extractants viz. ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA), calcium chloride (CaCl₂), Kelowna, Mehlich-III, ammonium acetate (NH₄OAc), and sodium tetraphenylborate (NaTPB₄). The availability study of K followed the pattern as, CaCl₂ < AB-DTPA < Kelowna < NH₄OAc < Mehlich-III < sodium tetraphenylborate (NaTPB₄). A higher extractability of K was envisaged under the conjoint application of higher doses of K fertilizers along with the organics. Among the extractants, NaTPB₄ showed the highest correlation sum (3.98) and also yielded a significant relationship with plant tissue K concentration (0.858) and uptake (0.715). The NaTPB₄, Mehlich-III, and NH₄OAc extractants were found to be significantly related to most of plant indices. The Euclidean distance based cluster analysis and linear regression study further proved the relatively higher efficiency of NaTPB₄ extractant followed by Mehlich-III and NH₄OAc to estimate plant K response in broccoli under the Gangetic alluvial soils of West Bengal, India.

Keywords:

• broccoli
• cluster analysis
• crop response
• inceptisol
• potassium (K)
• sodium tetraphenylborate (NaTPB₄)
• suitable extractants

Conflict of interest

There exists no conflict of interest among the authors.

Additional information

Funding

The financial assistance of AICRP-STCR from Indian Institute of Soil Science, Indian Council of Agricultural Research (ICAR-IISS), Bhopal- 462038, Madhya Pradesh, India for the research execution is gratefully acknowledged by the authors.