Abstract
Cropping sequence diversification provides a systems approach to reduce yield variations and improve resilience to multiple environmental stresses. Yield advantages of more diverse crop rotations and their synergistic effects with reduced tillage are well documented, but few studies have quantified the impact of these management practices on yields and their stability when soil moisture is limiting or in excess. Using yield and weather data obtained from a 31-year long term rotation and tillage trial in Ontario, we tested whether crop rotation diversity is associated with greater yield stability when abnormal weather conditions occur. We used parametric and non-parametric approaches to quantify the impact of rotation diversity (monocrop, 2-crops, 3-crops without or with one or two legume cover crops) and tillage (conventional or reduced tillage) on yield probabilities and the benefits of crop diversity under different soil moisture and temperature scenarios. Although the magnitude of rotation benefits varied with crops, weather patterns and tillage, yield stability significantly increased when corn and soybean were integrated into more diverse rotations. Introducing small grains into short corn-soybean rotation was enough to provide substantial benefits on long-term soybean yields and their stability while the effects on corn were mostly associated with the temporal niche provided by small grains for underseeded red clover or alfalfa. Crop diversification strategies increased the probability of harnessing favorable growing conditions while decreasing the risk of crop failure. In hot and dry years, diversification of corn-soybean rotations and reduced tillage increased yield by 7% and 22% for corn and soybean respectively. Given the additional advantages associated with cropping system diversification, such a strategy provides a more comprehensive approach to lowering yield variability and improving the resilience of cropping systems to multiple environmental stresses. This could help to sustain future yield levels in challenging production environments.
Highlights
IntroductionVulnerability of agroecosystems to variations in weather is of increasing concern as abnormal production scenarios associated with predicted changes in climate may become more common [1,2,3,4,5,6,7,8]
Vulnerability of agroecosystems to variations in weather is of increasing concern as abnormal production scenarios associated with predicted changes in climate may become more common [1,2,3,4,5,6,7,8].PLOS ONE | DOI:10.1371/journal.pone.0113261 February 6, 2015Cropping System Diversity and ResilienceWhile northern corn and soybean production regions may benefit from a longer crop-growing period, additional summertime warming and heavy rainfall events may challenge productivity unless adaptive measures are taken
The magnitude of rotation benefits varied with crops, weather patterns and tillage (Fig. 3), yield stability significantly increased when corn and soybean were integrated into more diverse rotations, especially when legumes were introduced (Fig. 3, Fig. 4)
Summary
Vulnerability of agroecosystems to variations in weather is of increasing concern as abnormal production scenarios associated with predicted changes in climate may become more common [1,2,3,4,5,6,7,8]. While northern corn and soybean production regions may benefit from a longer crop-growing period, additional summertime warming and heavy rainfall events may challenge productivity unless adaptive measures are taken. Projections from various climate models suggest that year-to-year variations will increase along with wetter spring conditions, drier summer months and greater frequency of abnormal precipitation events [9,10]. Increases in summer temperatures are projected to increase soil water evaporation and crop transpiration, further increasing soil water deficits and economic losses [11]
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