Potassium supply to cotton roots as affected by potassium fertilization and liming

• Main Authors: Rosolem Ciro Antonio, Silva Rosemeire Helena da, Esteves José Antonio de Fátima
• Format: Article
• Language: English
• Published: Embrapa Informação Tecnológica 2003-01-01
• Series: Pesquisa Agropecuária Brasileira
• Subjects: Gossypium hirsutum; mass; diffusion; liming materials; roots; growth; plant nutrition
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2003000500012

Cotton (Gossypium hirsutum) is known to have a high requirement for K and to be very sensitive to low soil pH. Most of K reaches plant roots by diffusion in the soil. As K interacts with Ca and Mg, liming can interfere in K movement in the soil, affecting eventually the plant nutrition. The objective of this work was to study the effect of dolomitic lime and 0, 15, 30, 45 and 60 g kg-1 of K on the supply of K to cotton roots. Cotton plants were grown up to 40 days in 5 L pots containing a Dark Red Latosol (Typic Haplusthox) with 68% and 16% of sand and clay, respectively. There was an increase in dry matter yields and in K accumulation due to K fertilization. Root interception of soil K was also increased by K application, but was not affected by lime. Mass flow and diffusion increased linearly with K levels up to 60 mg kg-1, in pots with lime. In pots without lime the amount of K reaching the roots by diffusion increased up to 45 mg kg-1, but decreased at the highest K level. Accordingly, there was more K reaching the roots through mass flow at the highest K level. This happened because there were more fine roots in pots without lime, at the highest K level. As the roots grew closer, there was a stronger root competition leading to a decrease in the amount of K diffused to cotton roots.