No abstract

No abstract

No abstract

Cultivating native lands may alter soil phosphorus (P) distribution and availability. The present study aimed to determine the distribution of P in soil aggregates for different long-term land management practices. The partitioned P in labile (L), Fe/Al-bound, Ca-bound, organic pools, and total P in four aggregate size fractions were determined for five land uses (forest, vineyard after 30 years, wetland, alfalfa, and wheat cultivated soil after 20 years). Both native land uses (forest and wetland) were distinguished by high and low amounts of large macro- and micro-aggregates, respectively, compared with disturbed soils (vineyard, alfalfa, and wheat soils). Labile P in large macro-aggregates were higher in native land use when compared with the other land uses, which led to increasing lability of P and accelerated water pollution. Soils under native conditions sequestered more Ca-bound P in large macro-aggregates than the soils in disturbed conditions. Conversion of native lands to agricultural land caused enhanced organic P storage in aggregates smaller than the 2 mm from 31.0 to 54.3%. Soils under forest had 30% total P more than the vineyard for the aggregates >2 mm after 30 years land use change. However, the amount of P in smaller (<2 mm) sized aggregates was increased by 29% for the vineyard when compared with the forest. The P storage as bound Ca particles for the large macro-aggregates had negative correlation with the micro-aggregates.

This research is aimed to study comparison of the effects of applied nanozeolite and zeolite on aggregation and organic carbon (OC) in each aggregate size fraction in treated soil with different levels of some plant residues and incubation for 90 days. The analysis of variance showed that the effects of applied nanozeolite, zeolite, plant residues, and their interaction and incubation times on MWDw and OC in aggregate size fractions were statistically significant. The results showed that MWDw and OC contents in each aggregate size fraction increased with the additions of nanozeolite, zeolite, and plant residues. This study also revealed that nanozeolite and alfalfa straw were more effective for increasing the MWDw and OC contents in aggregate size fractions than zeolite and wheat straw, respectively. In other words, higher percentage nanozeolite, zeolite, and plant residues resulted in increasing the MWDw and OC in aggregate size fractions. The highest amounts of OC were observed in A and B compounds compared with the control and other treatments. However, the comparison of OC contents in all the treatments showed that proportion of nanozeolite for increasing the OC content was greater than that of zeolite. Also the highest OC contents were observed in larger aggregate size fractions. The MWDw and OC contents increased with the increasing days of incubation in treated soil. Thus, it was concluded that compound A can be more effective to improve the soil carbon sequestration.

Organic carbon (OC) fractions play an important role in soil and many ecosystem processes. This study focuses on changing of OC in different fractions in a soil treated with different levels of zeolite and plant residue that incubated for 90 days. The results showed that the amounts of light fraction (LF) and heavy fraction (HF) increased with increasing the percentage of zeolite and plant residues in the soil. The highest amounts of LF (22.7 g LF. Kg-1 Soil) and HF (26.7 g. Kg-1 Soil) were found when 30% zeolite, 5% wheat and alfalfa straws was added to the soil respectively. Accordingly, wheat straw and alfalfa straw were effective for increasing the LF and HF respectively. However they declined with decreasing the OC from the 1 st day of experiment until the 90 th day of experiment. Soluble OC in hot (2.80 g. Kg-1 Soil) and cool (2.25 g. Kg-1 Soil) water fractions increased with the addition of 30% zeolite and 5% plant residues particularly alfalfa straw in comparison with control. Although they increased after 30 days of starting incubation but, then they decreased in the continuation of the experiment. In fact, OC contents in density and soluble fractions increased with application and addition of 30% zeolite and 5% plant residues into the soil; however they decreased after 30 days of incubation with decreasing the OC. The findings of this research revealed the application of zeolite and plant residues improved carbon pools in density and soluble fractions and carbon sequestration increase by increasing the OC contents in soil.

No abstract

No abstract