Investigation of different organic fertilizers application on the soil water holding capacity

This study was conducted to investigate the impacts of organic fertilizers on soil water holding capacity in four different suctions (0, 0.05, 0.33 and 15 bar) and their impacts on water retention curve in three different soil textures in five governing climates of Iran, which were cultivated under wheat and maize for two consecutive years. Furthermore, the role of organic materials in aggregation process was surveyed. The influence of organic materials on soil water holding capacity was evaluated in five treatments, including 10000, 20000 kg/ha of animal manures; 10000, 20000 kg/ha of compost, and control treatment in factorial and completely randomized statistical design. The results revealed that the addition of materials resulted into an increase in the mean weight diameter of soils aggregates with more concentration on 250-500 and 500-1000µ diameter. Additionally, the improvement of soil aggregation was more in sandy loam soil and less in clay loam soil. Interestingly, the role of organic materials in increasing soil water holding capacity in different plants and consecutive years was not significant.  By adding organic materials in field capacity and permanent wilting point, soil volumetric moisture increased far better than other studied soil moisture points. Sandy loam texture and semi-arid climates indicated the greatest variability to the additional organic materials. In conclusion, compost fertilizer in arid and semi-arid climates with sandy loam texture had the most influence on soil water holding capacity, particularly in FC and PWP moisture points