TITLE:
Effects of Zero Tillage and Residue Retention on Soil Quality in the Mediterranean Region of Northern Syria
AUTHORS:
Rolf Sommer, Colin Piggin, David Feindel, Muhammad Ansar, Lona van Delden, Kayoko Shimonaka, Jihad Abdalla, Osama Douba, George Estefan, Atef Haddad, Rousheen Haj-Abdo, Ali Hajdibo, Pierre Hayek, Yaseen Khalil, Ahmed Khoder, John Ryan
KEYWORDS:
Conservation Agriculture; Soil Fertility Indicators; Soil Water Evaporation; Water Infiltration; Water Stable Aggregates; Soil Carbon Sequestration
JOURNAL NAME:
Open Journal of Soil Science,
Vol.4 No.3,
March
31,
2014
ABSTRACT: Zero-tillage (ZT) and crop residue retention on the
soil surface—two components of
Conservation Agriculture (CA)—have been identified as promising management practices for sustainable
agri- cultural intensification for
some time. However, CA technology uptake by farmers in the dry areas of West
Asia and North Africa (WANA) has yet to happen large-scale, even though the
positive im- pact on yield has been
demonstrated repeatedly. To explain the observed consistent increases in crop
yield under ZT, a range of soil quality indicators were regularly monitored
during 2008 to 2012 in the long-term ZT/CA trials at the headquarters of the
International Center for Agricultural Research in the Dry Areas (ICARDA) in
northern Syria. Results showed that CA had a positive im- pact on soil fertility. This was measurable by higher soil organic
matter (SOM) and microbial bio- mass contents, increased
levels of extractable phosphate, sometimes (but not always) higher amounts of
larger water-stable soil aggregates, increased soil infiltration capacity and
soil water retention. The buildup of SOM and associated carbon (C)
sequestration was in the range of 0.29 Mg C/ha/yr, i.e. rather modest. High amounts of surface residues delayed the
desiccation of the topsoil during the fallow period, but could not diminish the
overall longer-term drying of the topsoil. The observed positive changes in
soil quality were little, but nevertheless, in combination with the economic
savings that ZT offers, this type of agricultural intensification provides an
attractive op- tion for farmers in WANA,
from the standpoints of economy and ecological efficiency.