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Soil Organic Carbon Changes to Increasing Cropping Intensity and No‐Till in a Semiarid Climate
Author(s) -
Engel Richard E.,
Miller Perry R.,
McConkey Brian G.,
Wallander Roseann
Publication year - 2017
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/sssaj2016.06.0194
Subject(s) - tillage , cropping system , perennial plant , soil carbon , summer fallow , agronomy , environmental science , conventional tillage , cropping , zoology , soil water , crop , biology , agriculture , ecology , soil science
Core Ideas After 10‐yr, NT annual cropping systems resulted in greater soil organic C mass relative to tilled fallow‐wheat. Cropping system intensity was more important to SOC mass than tillage. Changes in SOC mass were directly related to NPP and total C inputs. Annual cropping with NT management resulted in greater SOC mass (0–30 cm) than F‐W systems. SOC accretion was greatest in the CRP system. Soil organic C (SOC) in the semiarid Northern Great Plains (NGP) can benefit from increasing cropping intensity. We evaluated the effect of annual cropping on stocks of SOC adjusted for equivalent mass (SOC EM ; 0–30 cm) and the change in SOC adjusted for equivalent mass (ΔSOC EM ) over 10‐yr at a field site (45°40′N, 111°09′ W) near Bozeman, MT. The experiment consisted of two fallow‐wheat ( Triticum aestivum L.; F‐W) rotations under till and no‐till (NT), and five annual cropping systems under NT factored with two N levels (moderate and high), and alfalfa–perennial grass system (Conservation Reserve Program, CRP). After 10‐yr, we found SOC EM of five NT annual cropping ( X ¯ = 37.4 Mg ha –1 ) was significantly ( P < 0.01) greater than NT F‐W (35.1 Mg ha –1 ), and till F‐W (33.7 Mg ha –1 ). The greatest SOC EM was found in CRP (39.9 Mg ha –1 ). Accretion of SOC EM was observed in three systems with the largest gains occurring in the CRP (0.24 Mg ha –1 yr –1 ), followed by NT continuous wheat (0.13 Mg ha –1 yr –1 ) and NT pea ( Pisum sativum L.)/oil seed–wheat (0.09 Mg ha –1 yr –1 ). Soil organic C loss was observed in all other systems with the largest loss in the till F‐W (–0.29 Mg ha –1 yr –1 ). Among the cropping systems, ∆SOC EM was directly related to net primary productivity (NPP; r 2 = 0.73) and total C (TC; shoot + root + rhizodeposit) inputs ( r 2 = 0.86). We found SOC EM was maintained at 7.0 Mg ha –1 yr –1 of net primary productivity (NPP) and 2.6 Mg ha –1 yr –1 of TC inputs with accretion and loss occurring above and below these thresholds.