Investigation of size distribution of particles and aggregative soil under the effect of using two types of plant residuals

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Majid Mahmood Abadi ¹

1 - Assist. Prof., Dept. of soil science, Agriculture Faculty, Shahid Bahonar University of Kerman, Kerman, Iran

Received: 2011-06-05 Accepted : 2012-03-02 Published : 2012-03-02

Keywords: Aggregation, organic matters, soil structure,

Abstract :

Particle size distribution (PSD) and aggregate stability are two physical properties are important for soil conservation. This study investigates the effect of using different organic matters on the PSD in the wet and dry conditions. The experiment was conducted in randomized complete design with two plant residue treatments namely (straw stubble and pistachio residue) and three moisture levels namely 0, 1 and 5% water by weight in three replications. In addition, soil PSD was measured in two manners; dry (DPSD) and wet (WPSD). The results showed that the above treatments had different influences on the PSD, depending on the type and amounts of added plant residue and large aggregates used. For the DPSD, median sizes of aggregates in control, straw stubble (1 %w), pistachio residue (1 %w), straw stubble (5 %w) and pistachio residue (5 %w) were 0.228, 0.250, 0.227, 0.394 and 0.294 mm, respectively. In comparison to the results of DPSD relative to wet most frequent practices shifted from 0.125-0.25 mm particles to smaller than 0.125 mm. This finding indicated that the DPSD and WPSD do not follow the same trend. In addition, study of the WPSD indicated that addition of organic matters, aggregation improved and as a result larger aggregates were formed. It was also determined that application of different organic residues resulted in different amount of aggregation so that this effect was more pronounced in some sizes of aggregates.