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

• Published in: European journal of soil science Vol. 68; no. 5; pp. 658 - 666
• Main Authors: Rosolem, C. A., Steiner, F.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2017; Wiley Subscription Services, Inc
• Subjects: Agricultural practices; Agrochemicals; Clay; Clay loam; Clay soils; Cover crops; Crop yield; Cropping systems; Dynamics; Fertilizers; Grain; Leaching; Loam; Loam soils; Mineral nutrients; Potassium; Sandy soils; Soil; Soil dynamics; Soil investigations; Soil profiles; Soil properties; Soil texture; Soil types; Splitting; Sustainable agriculture; Texture; Tropical climate; Tropical environments
• ISSN: 1351-0754; 1365-2389
• DOI: 10.1111/ejss.12460

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 Botucatu, São Paulo, Brazil, 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.