Soil carbon saturation, productivity, and carbon and nitrogen cycling in crop-pasture rotations

M. Virginia Pravia, Armen Ricardo Kemanian, José A. Terra, Yuning Shi, Ignacio Macedo, Sarah Goslee

Research output: Contribution to journalArticle

Abstract

Agricultural systems integrating perennial grass-legume pastures in rotation with grain crops sustain high crop yields while preserving soil organic carbon (C s ) with low nitrogen (N) fertilizer inputs. We hypothesize that C s saturation in the topsoil may explain the favorable C and N cycling in these systems. We tested this hypothesis by evaluating and simulating three contrasting crop and pasture rotational systems from a 20-year no-till experiment in Treinta y Tres, Uruguay. The systems were: 1) Continuous annual cropping (CC); 2) crop-pasture rotation with two years of crops and four years of pastures (CP); and 3) perennial pasture (PP). Using the Cycles agroecosystems model, we evaluated the inclusion or exclusion of a C s saturation algorithm. The model simulated forage, soybean, and sorghum grain yields correctly, with low root mean square error (RMSE) of 1.5, 0.7 and 1.0 Mg ha −1 , respectively. Measurements show C s accretion and C s decline for the first and second half of the experiment, respectively. The C s accretion rate was highest for PP, while the C s decline was highest for CC (1.3 vs −0.6 Mg ha −1 y −1 of C). The model captured this C s dynamics and performed better when using the C s saturation algorithm than when excluding it (RMSE 4.7 vs 6.8 Mg C ha −1 and relative RMSE of 14% and 21% for the top 15-cm). The model with saturation simulated subsoil C s distribution with depth well, and simulated faster N turnover and greater N availability for the subsequent grain crop in CP vs CC. The results suggest that C s saturation, and by extension soil organic N saturation, underpin the sustainability of crop-pasture rotations, and that modeling C s saturation dynamics can be critical to reliably simulate complex crop-pasture rotational systems.

Original languageEnglish (US)
Pages (from-to)13-22
Number of pages10
JournalAgricultural Systems
Volume171
DOIs
StatePublished - May 1 2019

Fingerprint

pastures
carbon
nitrogen
crops
soil
grain crops
nitrogen fertilizers
crop year
forage legumes
Uruguay
agroecosystems
subsoil
Sorghum (Poaceae)
organic soils
soil organic carbon
topsoil
no-tillage
crop yield
grain yield
forage

All Science Journal Classification (ASJC) codes

  • Animal Science and Zoology
  • Agronomy and Crop Science

Cite this

Pravia, M. Virginia ; Kemanian, Armen Ricardo ; Terra, José A. ; Shi, Yuning ; Macedo, Ignacio ; Goslee, Sarah. / Soil carbon saturation, productivity, and carbon and nitrogen cycling in crop-pasture rotations. In: Agricultural Systems. 2019 ; Vol. 171. pp. 13-22.
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abstract = "Agricultural systems integrating perennial grass-legume pastures in rotation with grain crops sustain high crop yields while preserving soil organic carbon (C s ) with low nitrogen (N) fertilizer inputs. We hypothesize that C s saturation in the topsoil may explain the favorable C and N cycling in these systems. We tested this hypothesis by evaluating and simulating three contrasting crop and pasture rotational systems from a 20-year no-till experiment in Treinta y Tres, Uruguay. The systems were: 1) Continuous annual cropping (CC); 2) crop-pasture rotation with two years of crops and four years of pastures (CP); and 3) perennial pasture (PP). Using the Cycles agroecosystems model, we evaluated the inclusion or exclusion of a C s saturation algorithm. The model simulated forage, soybean, and sorghum grain yields correctly, with low root mean square error (RMSE) of 1.5, 0.7 and 1.0 Mg ha −1 , respectively. Measurements show C s accretion and C s decline for the first and second half of the experiment, respectively. The C s accretion rate was highest for PP, while the C s decline was highest for CC (1.3 vs −0.6 Mg ha −1 y −1 of C). The model captured this C s dynamics and performed better when using the C s saturation algorithm than when excluding it (RMSE 4.7 vs 6.8 Mg C ha −1 and relative RMSE of 14{\%} and 21{\%} for the top 15-cm). The model with saturation simulated subsoil C s distribution with depth well, and simulated faster N turnover and greater N availability for the subsequent grain crop in CP vs CC. The results suggest that C s saturation, and by extension soil organic N saturation, underpin the sustainability of crop-pasture rotations, and that modeling C s saturation dynamics can be critical to reliably simulate complex crop-pasture rotational systems.",
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Soil carbon saturation, productivity, and carbon and nitrogen cycling in crop-pasture rotations. / Pravia, M. Virginia; Kemanian, Armen Ricardo; Terra, José A.; Shi, Yuning; Macedo, Ignacio; Goslee, Sarah.

In: Agricultural Systems, Vol. 171, 01.05.2019, p. 13-22.

Research output: Contribution to journalArticle

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AU - Pravia, M. Virginia

AU - Kemanian, Armen Ricardo

AU - Terra, José A.

AU - Shi, Yuning

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AU - Goslee, Sarah

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