A. Saviozzi et al., LABORATORY STUDIES ON THE APPLICATION OF WHEAT-STRAW AND PIG SLURRY TO SOIL AND THE RESULTING ENVIRONMENTAL IMPLICATIONS, Agriculture, ecosystems & environment, 61(1), 1997, pp. 35-43
In a laboratory experiment, wheat straw (WS), pig slurry (PS) and a mi
xture of the two materials (WSPS) were added to soil at the rate of 2%
on a dry soil basis. Samples of the soil alone and with the amendment
s were collected at various intervals of time during a one year period
and analysed for: pH, electrical conductivity (EC.), NO3-, HPO42-, ph
enolic compounds and volatile acids. A germination index (G.I) using t
he Lepidium sativum test was carried out. The fractionation of the dif
ferent forms of Cu and Zn was investigated. In comparison with the con
trol, the WS-treated soil showed a constant diminution of NO3-, a slig
ht lowering of pH and a net increase of EC. Sixty days after amendment
, phenolic compound and volatile acid contents became equal to those o
f the control, The WS did not show any germination effect and did not
significantly influence the content and distribution of soil Cu and Zn
. The addition of PS to soil produced an increase of EC., NO3- and HPO
42-,2-, with a consequent lowering of the pH, a moderate effect on phe
nolic substances and volatile acids and a toxic effect on seed germina
tion until the 7(th) day after the amendment. Total levels of Cu and Z
n and their organic and inorganic bound fractions increased. The most
consistent effect on soil properties from the WSPS mixture was for NO3
-, which was released slowly but progressively. This mixture increased
the germination index in comparison with PS added alone to the soil.