Increasing Cropping System Diversity Balances Productivity, Profitability and Environmental Health

Abstract

Balancing productivity, profitability, and environmental health is a key challenge for agricultural sustainability. Most crop production systems in the United States are characterized by low species and management diversity, high use of fossil energy and agrichemicals, and large negative impacts on the environment. We hypothesized that cropping system diversification would promote ecosystem services that would supplement, and eventually displace, synthetic external inputs used to maintain crop productivity. To test this, we conducted a field study from 2003–2011 in Iowa that included three contrasting systems varying in length of crop sequence and inputs. We compared a conventionally managed 2-yr rotation (maize-soybean) that received fertilizers and herbicides at rates comparable to those used on nearby farms with two more diverse cropping systems: a 3-yr rotation (maize-soybean-small grain + red clover) and a 4-yr rotation (maize-soybean-small grain + alfalfa-alfalfa) managed with lower synthetic N fertilizer and herbicide inputs and periodic applications of cattle manure. Grain yields, mass of harvested products, and profit in the more diverse systems were similar to, or greater than, those in the conventional system, despite reductions of agrichemical inputs. Weeds were suppressed effectively in all systems, but freshwater toxicity of the more diverse systems was two orders of magnitude lower than in the conventional system. Results of our study indicate that more diverse cropping systems can use small amounts of synthetic agrichemical inputs as powerful tools with which to tune, rather than drive, agroecosystem performance, while meeting or exceeding the performance of less diverse systems.

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…Crop rotation is widely recognized as a useful tool for weed, disease, and insect management, as well as soil health and nutrient management, and the positive effects of varying crop sequences on crop yields are well documented (e.g., Arshad et al 2002;Campbell et al 2011;Davis et al 2012). Strategic inclusion of diverse species that encompass a wide range of functional groups helps to create cropping systems that effectively support key ecological processes (Altieri 1999;Entz et al 2002;Drinkwater and Snapp 2007;Lin 2011).…”

“…Diversified crop rotations have been observed to increase overall yield, provide more stable profits over time, and reduce input requirements (Smith et al 2008;Davis et al 2012). They also have reduced potential for nitrate leaching (Malhi et al 2009) and tend to be more efficient in their energy use and produce lower levels of GHG emissions (Zentner et al 2011b).…”

“…However, considerable potential exists to enhance the cycling of nutrients within cropping systems so that external inputs can be minimized. Davis et al (2012) suggest that productivity and environmental sustainability can be optimized in a system that is driven by endogenous inputs and ''tuned'' using small amounts of external inputs.…”

“…Use of animal manure as a nutrient source for crops has diminished with the separation of crop and livestock production systems and the availability of easy-to-use synthetic fertilizers (Davis et al 2012). As a result, animal manure is often treated as a waste product rather than as a source of fertility and organic matter for cropping systems.…”

Cost-effective targeting of conservation investments to reduce the northern Gulf of Mexico hypoxic zone

“…Another limitation is that not all potentially cost-effective conservation actions were simulated in our analysis, including some promising new approaches to retain nutrients on the landscape (e.g., bioreactors, saturated buffers, and cover crops) (22,23). Likewise, the options we considered were only "working land" options, i.e., cropland conservation scenarios that are consistent with maintaining current crop production levels, because the practices modeled do not require changes in the cropping systems (11)(12)(13)(14)(15).…”