Data/hora: 23/09/2024 02:34:51

Biblioteca(s): 	Embrapa Solos.	
Data corrente: 	15/05/2017	
Data da última atualização: 	11/11/2021	
Autoria: 	VOLF, M.; BENITES, V. de M.; ROSOLEM, A. C.; CRUSCIOL, A. C.; MORAES, F. M.; MENEZES, F. J.; SILVA, C. A.	
Afiliação: 	MARCELO RAPHAEL VOLF, UNESP; VINICIUS DE MELO BENITES, CNPS; CIRO ANTONIO ROSOLEM, UNESP; CARLOS ALEXANDRE COSTA CRUSCIOL, UNESP; MILTON F. MORAES, UFMT; JUNE FARIA SCHERRER MENEZES, UNIRV; ANA C. SILVA, DALCIN LABORATORY OF SOIL AND PLANT.	
Título: 	Silt as K source for crops in tropical soils.	
Ano de publicação: 	2017	
Fonte/Imprenta: 	In: FRONTIERS OF POTASSIUM SCIENCE CONFERENCE, 2017, Rome. Proceedings... Peachtree Corners: International Plant Nutrition Institute, 2017. Ref. P185-P193.	
Idioma: 	Inglês	
Conteúdo: 	The original soil exchangeable potassium (K) concentrations are at or above critical levels in many Brazilian Cerrado (savanna) soils. Hence, many cropped areas have been fertilized with low K rates, below crop requirements, but yields have not decreased as expected. In these areas, topsoil exchangeable K analyses have shown no decrease, or even some increase. The aim of this study was to evaluate exchangeable and non-exchangeable K forms in soils under different uses and managements in the Vale do Araguaia region of Mato Grosso state, Brazil. Soil samples were taken from 91 sites at depths of 0-20 cm and 20-40 cm, in areas under grain crops, pasture and native vegetation (Cerrado or forest). Silt content ranged from 12 to 175 g kg-1 and clay from 90 to 595 g kg-1, and the predominant clays were kaolinite, hematite, goethite and gibbsite. Under pasture, the soils had high levels of exchangeable K in the 0-20 cm layer and high levels of non-exchangeable K from 20 to 40 cm. This can be a result of the absorption of non-exchangeable K by grasses, the main cultivated species, by recycling K to the exchangeable fraction in the topsoil. There was a positive relationship between silt and non-exchangeable K contents. Ratios of exchangeable to non-exchangeable K were over 3 in soils with silt above 70 g kg-1, in which non-exchangeable K was over 100 mg dm-3. Cover crops growing in soils rich in silt take up non-exchangeable K and exchangeable K from deeper layers, which is recycled to the soil as exchangeable K upon plant residue mineralization, which may have been responsible for the maintenance or increase in exchangeable K levels in the 0-20 cm layer in areas where low K rates have been used for grain production.	
Palavras-Chave: 	Vale do Araguaia.	
Thesagro: 	Cerrado; Solo.	
Categoria do assunto: 	P Recursos Naturais, Ciências Ambientais e da Terra	
URL: 	http://ainfo.cnptia.embrapa.br/digital/bitstream/item/159821/1/2017-004.pdf	
Registro original: 	Embrapa Solos (CNPS)	
Exemplares: 	CNPS - (19587-1) - UPC - AA - DD -  -  - 2017.00147 - DIS