In which circumstance is potassium deficiency most likely to occur?

Potassium deficiency is most likely to occur under circumstances where the nutrient's availability is limited due to soil characteristics and management practices. In the given options, high clay content combined with a high pH can lead to reduced potassium availability.

In this case, the presence of 20% kaolinite clay in option B contributes to a more compact soil structure, which can restrict root growth and the ability of plants to access potassium. Furthermore, a pH of 8.3 is on the higher end of the pH scale, which can negatively affect the solubility and mobility of potassium in the soil. Additionally, double-cropping intensifies the nutrient demand on the soil, increasing the likelihood of potassium depletion due to continuous harvesting without adequate replenishment.

Other scenarios may have favorable conditions that mitigate potassium deficiency. Soils with high organic matter generally improve nutrient retention, and a loamy texture (as seen in other options) can provide balanced drainage and nutrient availability. Monoculture and rotating crops may enhance nutrient cycling but do not inherently create deficiencies as severe as those found in long-term high-demand cropping situations without adequate nutrient management strategies. Thus, the combination of the clay content, high pH, and intensive cropping makes option B the most