Effects of soil texture and rates of K input on potassium balance in tropical soil

The efficiency of potassium ( K ) fertilizer use is important in sustainable agriculture and is affected by losses related to soil texture. However, there is no information on how much K is lost by leaching in tropical soil. The effects of rates of fertilizer‐ K application on K dynamics and budget in a soil–plant system at depths up to 1 m were studied in B otucatu, S ão P aulo, B razil, from 2000 to 2012; soil types were a sandy clay loam (250 g clay kg −1 ) and a clay soil (670 g clay kg −1 ) under no‐till management. The soils were fertilized annually with 0, 25, 50, 75, 100, 125 and 150 kg  K  ha −1 . Annual applications of 50–75 kg  K  ha −1 to the sandy clay loam soil and 25–50 kg  K  ha −1 to the clay soil were sufficient to achieve a large grain yield and maintain soil exchangeable K in the soil profile. An annual application of up to 150 kg  K  ha −1 to clay soil does not result in a large amount of leaching below 1‐m depth. Non‐exchangeable K plays an important role in tropical cropping systems. The increase in rates of fertilizer‐ K application intensifies losses by leaching below 1 m in sandy clay loam soil, which represents 16–52% of the K added as fertilizer. Therefore, because of the considerable leaching potential, splitting the applications of K is an important management strategy to minimize losses and improve the efficiency of K use in tropical soil with small clay contents. Highlights We investigated the effect of soil texture on K movement in the profile. Losses of K were estimated in a cropping system with cover crops. In tropical soil clay content plays an important role in the movement of K in the soil profile. In clay soil K losses are small, but can be up to 52% of the nutrient applied to sandy soil.