Data/hora: 23/06/2024 20:29:56

Biblioteca(s): 	Embrapa Meio Norte / UEP-Parnaíba.	
Data corrente: 	28/08/1992	
Data da última atualização: 	03/03/2009	
Autoria: 	MIYAMOTO, S.	
Título: 	Sampling irrigated soils for salinity appraisal.	
Ano de publicação: 	1983	
Fonte/Imprenta: 	[S. l.: s. n., 19--].	
Páginas: 	12 p.	
Idioma: 	Inglês	
Conteúdo: 	This report outlines the distribution and variation characteristics of soil salinity in irrigated fields statistical treatments of the variability, and sampling strategies for salinity appraisal. The data were obtained from five border- or basin-irrigated and four furrow-irrigated fields in the El Paso Valley, Texas. The coefficient of variability (CV) for salinity ranged from 17 to 47 percent with a mean CV of 30 percent in 0.5 to 6.2 hectare (ha) areas of the border- or basin-irrigated fields. The CV values for 103 to 178 meters (m) of furrow-irrigatd crop beds immediately before preplant irrigated were comparatively low (19 percent) but increased with repeated irrigations to an average value of 31 percent. The CV values for sodicity somewhat smaller. The saturation water content (a measure ofsoil texture) accounted for 62 percent of salinity variation in a border-irrigated orchard and less than 40 percent in the furrow-irrigated fields. In both cases, the distance from irrigation ditches was not the substantial factor governing salinity distribution. The analysis of autocorrelation showed that soil salinity in one of the furow-irrigated fields was spatially dependent up to 46 m, but the distance of dependence decresased to less tha 15 m when salinity readings were stratified by soil type. The frequency distribution of salinity and sodicity averaged over sampling depths and stratified by soil type conformed to the normal distribution. The number of soil samples required to obtain the mean value within 15 percent of the true mean averaged 13 per 0.5 to 3.4 ha areas of the border- or basin-irrigated fields, and 6 per tested row lengths. The sampling requirement generally increased with increasing sampling depth. For routine appraisal, soil samples (of the quantities specified above) can be collected on the basis of soil type or crop growth. The measured mean salinity plus the standard deviation may serve as a practical index for appraising salt effects on crop performance in the sampled area. 	
Palavras-Chave: 	Amostra.	
Thesagro: 	Irrigação; Salinidade; Solo.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Meio Norte / UEP-Parnaíba (CPAMN-UEPP)	
Exemplares: 	CPAMN-UEPP - (1275-1) - ADD - FL - -- - FOL 1975/1992 -  - 1992.01975 - DIS