Opposite effects of two organic wastes on the physical quality of an agricultural soil

Abstract

Soil application of organic wastes (OW) can be beneficial for soil quality, depending on the quality of the wastes as well as on the amended soil. We performed a field experiment comparing the effects of two different organic wastes, an industrial sewage sludge (ISS) and a municipal solid waste compost (MSWC), on the physical, chemical and biological quality of an agricultural soil cultivated with maize in central Iran. The two OW were mixed into the topsoil of the plots at rates of 15 and 45 t haP -1 P (dry matter). The analysis of soil samples taken 31, 74, 132 and 241 days after OW application showed, both OW increased organic matter, microbial respiration, and urease activity and decreased bulk density. In contrast, they had opposite effects on water retention and saturated hydraulic conductivity. While the MSWC increased water retention at high saturation and saturated hydraulic conductivity, the ISS decreased them. The negative effects of the ISS on physical soil quality, which may have been due to pore-clogging and hydrophobicity effects, were related to a smaller yield increase A c c e p t e d M a n u s c r i p t Downloaded by [New York University] at 10:01 09 June 2015in the ISS than in the MSWC treatments, demonstrating the importance that physical organic waste properties can have for the quality of amended soil.

Soil water repellency changes with depth and relationship to physical properties within wettable and repellent soil profiles

“…The repellent soil had greater MWD dry than the wettable soil at all depths except at the surface (0-10 cm). Various factors affect soil aggregate stability (Amezketa, 1999;Sepehrnia et al, 2014;Zamani et al, 2016) but such distinct differences in MWD dry , small BD, and hydrophobicity can be due to multiple effects of organic matter (Table 1). One driver is the coating of hydrophobic materials around the repellent soil aggregates that would decrease slaking stresses due to a slower inflow of water upon wetting.…”

Can Organic Amendments Improve Soil Physical Characteristics and Increase Maize Performances in Contrasting Soil Water Regimes?

“…Liu et al [59] reported that after adding 20 t ha −1 compost in a Cambisol (FAO Soil Taxonomy) with a loamy-sand texture, the plant available water (between field capacity and wilting point) was increased twofold, from 6 to 12%. Many similar examples can be found [50,60,61]. However, a recent meta-analysis conducted on 60 published papers by Minasny and McBratney [62] reported that after OA addition, the total increase in available water capac-ity was generally very small (1.16 mm H 2 O 100 mm soil −1 ), and the water capacity increase was larger at saturation, followed by field capacity and wilting point.…”

“…We also made the hypothesis that different OA would affect crops differently. Zamani et al [50] have already demonstrated the differential effects of OA, from which sewage sludge decreased maize growth, whereas solid waste compost increased it. If only solid wastes are considered, vermicompost has a higher impact, but this is difficult to generalize as vermicomposts and composts were often prepared with different materials and technologies [51].…”

An Overview: Organic Waste Management by Earthworm

“…The organic waste of industrial sewage sludge and municipal solid waste compost were mixed with cultivated soil. The both treatment increased the organic matter, microbes, but decreased waster holding capacity in industrial waste, in case of the yield industrial waste was higher than municipal waste treated soil [46].…”