Continuous
wheat in semiarid regions: Long-term effects on stock and quality of soil
organic carbon
Continuous wheat (Triticum
aestivum L.) cropping in semiarid regions results in variable dry matter
production. As a consequence, the balance of soil organic carbon (SOC) may vary
over time. The aim of this research was to assess the dynamics and long-term
changes of physically and chemically extracted SOC fractions. Soil samples (0-5,
5-10 and 10-20 cm depths) from continuous wheat, with (f) and without (nf)
fertilizer (N+P) under conventional- (CT, for 25 y) and no-tillage (NT, for 6
y) were taken during the experiment. Mineral-associated (MOC, 0-0.053 mm), fine
particulate (POCf, 0.053-0.100 mm) and coarse particulate (POCc,
0.1-2.0 mm) SOC and humic substances were obtained. SOC variability was
depending on water availability during fallow periods (SOC decomposition) or
crop cycles (dry matter production). The mean wheat yields were 1.33 (nf) and
2.09 (f) Mg grain ha-1, with an estimated carbon input of 1.64 (nf)
and 2.20 (f) Mg C ha-1 yr-1. Losses from the initial
level were higher in labile fractions, POCc (-75%) and POCf
(-53%), than in MOC (-15%). Humic acids present slight differences in
their structure and quantity as a result of long-term cropping. Conversion from
CT to NT resulted in contrasting results. For an equivalent soil mass, fertilizer application
increased SOC by 4.31 Mg ha-1 (under CT) and 7.29 Mg ha-1
(under NT). The SOC turned out to be higher under NT with fertilizer use
and lower without application. No-tillage does not increase SOC content by itself; it must be combined
with other agricultural practices, such as fertilization and/or crop rotation.
Keywords: Fertilization, Tillage system, Physical
organic carbon fractions, Humic substances
Galantini
Juan A., Matias E. Duval, Julio O. Iglesias and Hugo Kruger. 2014. Continuous
wheat in semiarid regions: Long-term effects on stock and quality of soil
organic carbon. Soil Science 179: 284-292.
PDF in ResearchGate Mega
PDF in ResearchGate Mega
No comments:
Post a Comment