Influence of soil structure on contaminant leaching from injected slurry

Abstract

Animal manure application to agricultural land provides beneficial organic matter and nutrients but can spread harmful contaminants to the environment. Contamination of fresh produce, surface water and shallow groundwater with the manure-borne pollutants can be a critical concern. Leaching and persistence of nitrogen, microorganisms (bacteriophage, E. coli, and Enterococcus) and a group of steroid hormone (estrogens) were investigated after injection of swine slurry into either intact (structured) or disturbed (homogeneous repacked) soil. The slurry was injected into hexaplicate soil columns at a rate of 50 t ha and followed with four irrigation events: 3.5-h period at 10 mm h after 1, 2, 3, and 4 weeks. The disturbed columns delayed the leaching of a conservative tracer and microorganisms in the first irrigation event compared to the intact columns due to the effect of disturbed macropore flow paths. The slurry constituents that ended up in or near the macropore flow paths of the intact soil were presumably washed out relatively quickly in the first event. For the last three events the intact soil leached fewer microorganisms than the disturbed soil due to the bypassing effect of water through the macropore flow path in the intact soil. Estrogen leached from the intact soil in the first event only, but for the disturbed soil it was detected in the leachates of last two events also. Leaching from the later events was attributed to higher colloid transport from the disturbed soils. In contrast, NO-N leaching from the intact soil was higher for all events except the first event, probably due to a lower nitrification rate in the disturbed soil. A week after the last irrigation event, the redistribution of all slurry constituents except NO-N in most of the sections of the soil column was higher for the disturbed soil. Total recovery of E. coli was significantly higher from the disturbed soil and total leaching of mineral nitrogen was significantly lower from the disturbed soil. Results demonstrate how manure-borne constituents injected into undisturbed soil columns respond more as expected in the field, in terms of leaching and persistence, than do the same constituents injected into typically constructed columns of disturbed soil.

Nitrogen and phosphorus leaching and vegetative growth of maize as affected by organic manure application

“…Nahar et al (2006) reported that fresh manure loosened soil aggregates by increasing microbial activities more than the composted dry manure. The loose aggregates can facilitate soil water transport through its pore spaces (Amin et al, 2016). Manure application increased soil organic matter from 1.1 to 1.4-1.9% and electrical conductivity from 132 to 156-206 µS cm -1 but reduced bulk density from 1.33 to 1.25 g cm -3 in the topsoil.…”

Propriedades qualitativas do açafrão da terra manejado com fontes e doses de adubação

“…A aplicação da adubação por meio da utilização de fertilizantes orgânicos (esterco bovino e cama de aves) combinado com inorgânicos (NPK) proporcionou influência no melhor desenvolvimento vegetativo, no comprimento e na largura máxima da folha (Amin et al, 2016), que proporcionou área foliar (AF) e índice da área foliar (IAF) maiores na cultura do açafrão da terra.…”

Soil hydraulic properties and field-scale hydrology as affected by land-management options

“…Altered soil hydraulic properties may affect the transport of nutrients and contaminants (Amin et al, 2016). Dislodged colloids during puddling can remarkably influence the transportation of sorbing pollutants in the vadose zone.…”