Premium
Water‐Use Efficiency and Carbon Isotopic Composition in Reduced Tillage Systems
Author(s) -
Walley F. L.,
Matus A.,
Lafond G. P.,
Kessel C.
Publication year - 1999
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1999.03615995006300020013x
Subject(s) - agronomy , water use efficiency , tillage , summer fallow , crop rotation , crop residue , organic matter , environmental science , soil organic matter , conventional tillage , soil water , soil fertility , sativum , dry matter , crop , chemistry , biology , soil science , agriculture , cropping , ecology , organic chemistry , irrigation
Cropping systems that influence soil water availability are expected to influence the C isotopic composition (δ 13 C) of crop residues and consequently, the δ 13 C of soil organic matter. We hypothesized that the δ 13 C of plant residues and soil organic matter in three tillage systems (zero [ZT], minimum [MT], and conventional tillage [CT]) and three, 4‐yr crop rotations would vary and would relate to water‐use efficiency (WUE). The study was conducted on an Indian Head heavy clay (Udic Haploboroll) in Saskatchewan, Canada. The three crop rotations were fallow‐spring wheat ( Triticum aestivum L.)‐spring wheat‐winter wheat, spring wheat‐spring wheat‐flax ( Linum usitatissimum L.)‐winter wheat, and spring wheat‐flax‐winter wheat‐field pea ( Pisum sativum L.). Water use was estimated yearly using mass balance. The δ 13 C of the standing crop residue, roots, and soil organic matter was determined 9 yr after the study was initiated. Although crop water use was higher in ZT (31.2 cm yr ‐1 ) and MT (30.9 cm yr ‐1 ) than in CT (28.8 cm yr ‐1 ), corresponding differences in WUE and δ 13 C of plant tissue and soil organic matter were not detected. In one instance, within the most diversified rotation, WUE was reduced in ZT compared with CT; however, observed variations in WUE did not conform to theoretical expectations of the δ 13 C of plant residues and soil organic matter. Factors other than WUE, including soil fertility and timing of moisture deficits, may have influenced the degree to which C isotope discrimination was expressed in the plant residues and soil organic matter.