No abstract

The occurrence of wet and dry spells is a phenomenon most often used to identify the arid and semi-arid lands (ASAL) in Kenya. The use of first-order Markov processes that are embedded into a computer model to determine the critical climate extremes is presented. The model uses the concepts of conditional probability, Poisson probability distribution function and chi-square testing to predict the critical spells. The daily rainfall data (1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000) for two weather stations in the Kano Plains (Kenya) have been used to illustrate model application. For example, based upon the bimodal rainfall pattern in the study area, the model revealed the length of the critical dry spell to be 14 days in the long rainy season and 12 days in the short rainy season, while the critical wet spell was found to be 12 and 8 days, for the long and short rains respectively for Ahero Irrigation Scheme. It is recommended that a climate and environmental audit in the Kano Plains for the determination of land and water management strategies include critical dry and wet spell determination. This will enhance more sustainable planning and utilization of the crucial water and land resources in the region and in other tropical rangelands.

Soil salinization is directly related to the quantity and quality of food production, and often, to increased energy demands for high-quality irrigation water. Reliable monitoring of soil salinity based on a less laborious method than the soil saturated paste (SP) extract methodology is required. In the present study, an attempt is made to relate the electrical conductivity (EC) of the soil saturated paste (SP) extract (ECe) with the EC determined in the 1:1 and 1:5 soil over water mass ratios, (soil:water) extracts (EC1:1 and EC1:5). ECe, EC1:1, and EC1:5 values were obtained for 198 soil samples from five different locations in Greece. The results have shown that strong linear relationships exist between the ECe and the EC1:1 and EC1:5 values (R2 > 0.93), and that the slopes of these linear relationships decreased from coarse to fine soil types. For 123 soil samples, the concentrations of Κ+, Νa+, Ca2+, Mg2+, and Cl− were also determined in the extracts of the three applied methodologies. Ion concentrations in the 1:1 and 1:5 extracts were highly correlated with the respective ion concentrations in the SP extracts. These findings strongly suggest that EC1:1 and EC1:5 values can be safely used for the estimation of ECe.

No abstract

No abstract