Richard M. Cruse

Sustainable Biofuels Redux

Science-based policy is essential for guiding an environmentally sustainable approach to cellulosic biofuels.

Assessing alternative futures for agriculture in Iowa, U.S.A

The contributions of current agricultural practices to environmental degradation and the social problems facing agricultural regions are well known. However, landscape-scale alternatives to current trends have not been fully explored nor their potential impacts quantified. To address this research need, our interdisciplinary team designed three alternative future scenarios for two watersheds in Iowa, USA, and used spatially-explicit models to evaluate the potential consequences of changes in farmland management. This paper summarizes and integrates the results of this interdisciplinary research project into an assessment of the designed alternatives intended to improve our understanding of landscape ecology in agricultural ecosystems and to inform agricultural policy. Scenario futures were digitized into a Geographic Information System (GIS), visualized with maps and simulated images, and evaluated for multiple endpoints to assess impacts of land use change on water quality, social and economic goals, and native flora and fauna. The Biodiversity scenario, targeting restoration of indigenous biodiversity, ranked higher than the current landscape for all endpoints (biodiversity, water quality, farmer preference, and profitability). The Biodiversity scenario ranked higher than the Production scenario (which focused on profitable agricultural production) in all endpoints but profitability, for which the two scenarios scored similarly, and also ranked higher than the Water Quality scenario in all endpoints except water quality. The Water Quality scenario, which targeted improvement in water quality, ranked highest of all landscapes in potential water quality and higher than the current landscape and the Production scenario in all but profitability. Our results indicate that innovative agricultural practices targeting environmental improvements may be acceptable to farmers and could substantially reduce the environmental impacts of agriculture in this region.

Germination tests for assessing biochar quality.

Definition, analysis, and certification of biochar quality are crucial to the agronomic acceptance of biochar. While most biochars have a positive impact on plant growth, some may have adverse effects due to the presence of phytotoxic compounds. Conversely, some biochars may have the ability to adsorb and neutralize natural phytotoxic compounds found in soil. We evaluated the effects of biochars on seedling growth and absorption of allelochemicals present in corn ( L.) residues. Corn seeds were germinated in aqueous extracts of six biochars produced from varied feedstocks, thermochemical processes, and temperatures. Percent germination and shoot and radicle lengths were evaluated at the end of the germination period. Extracts from the six biochars had no effect on percent germination; however, extracts from three biochars produced at high conversion temperatures significantly inhibited shoot growth by an average of 16% relative to deionized (DI) water. Polycyclic aromatic hydrocarbons detected in the aqueous extracts are believed to be at least partly responsible for the reduction in seedling growth. Repeated leaching of biochars before extract preparation eliminated the negative effects on seedling growth. Biochars differ significantly in their capacity to adsorb allelochemicals present in corn residues. Germination of corn seeds in extracts of corn residue showed 94% suppression of radicle growth compared to those exposed to DI water; however, incubation of corn residue extracts with leached biochar for 24 h before initiating the germination test increased radicle length 6 to 12 times compared to the corn residue extract treatments. Germination tests appear to be a reliable procedure to differentiate between effects of different types of biochar on corn seedling growth.

Soil and Corn Response to Tillage with Paraplow

Corn (Zea mays L.) grown following corn, on poorly drained, fine-textured soils, with no-till tends to yield less than with other tillage systems. Surface residues conserved with no-till reduce erosion, thus, techniques must be found to avoid yield reductions. Field experiments were conducted to evaluate use of the Paraplow (Howard Rotovator Co., Inc.), a tillage tool that loosens soil without inversion, for continuous corn production. No-till, chisel plow, moldboard plow, and Paraplow systems were evaluated on three poorly drained, medium- and fine-textured soils in Iowa. All tillage tools reduced bulk density and penetration resistance to the depth of tillage. However, after planting only the soil tilled with the Paraplow remained less dense. Plant residue cover had more effect on corn growth than did soil loosening. Emergence and yield of corn were inversely related to amount of residue on soil surface after planting.

Sediment removal by prairie filter strips in row-cropped ephemeral watersheds

Twelve small watersheds in central Iowa were used to evaluate the effectiveness of prairie filter strips (PFS) in trapping sediment from agricultural runoff. Four treatments with PFS of different size and location (100% rowcrop, 10% PFS of total watershed area at footslope, 10% PFS at footslope and in contour strips, 20% PFS at footslope and in contour strips) arranged in a balanced incomplete block design were seeded in July 2007. All watersheds were in bromegrass ( L.) for at least 10 yr before treatment establishment. Cropped areas were managed under a no-till, 2-yr corn ( L.)-soybean [ (L.) Merr.] rotation beginning in 2007. About 38 to 85% of the total sediment export from cropland occurred during the early growth stage of rowcrop due to wet field conditions and poor ground cover. The greatest sediment load was observed in 2008 due to the initial soil disturbance and gradually decreased thereafter. The mean annual sediment yield through 2010 was 0.36 and 8.30 Mg ha for the watersheds with and without PFS, respectively, a 96% sediment trapping efficiency for the 4-yr study period. The amount and distribution of PFS had no significant impact on runoff and sediment yield, probably due to the relatively large width (37-78 m) of footslope PFS. The findings suggest that incorporation of PFS at the footslope position of annual rowcrop systems provides an effective approach to reducing sediment loss in runoff from agricultural watersheds under a no-till system.

Grain yield response of corn, soybean, and oat grown in a strip intercropping system

Conventional Midwestern U.S. row crop agriculture has created significant environmental problems and made the farm economy reliant on government subsidies. Environmentally friendly and economically profitable alternatives are badly needed. This study addresses production characteristics of strip intercropping, a system that may meet both requirements. Two experiments were conducted in 1989 and 1990: one on a cooperating farmers field with ridge tillage and the second at a university research farm with conventional tillage. The objective was to evaluate grain yields of different rows in adjoining strips (3.8 or 4.6 m wide) of three crops. Corn, soybean, and oat strips were either inter seeded with nondormant alfalfa or seeded with hairy vetch as a cover crop after oat grain harvest. Outside corn rows had significantly higher yields than center rows in 1990, when plant water stress was low, but under dry conditions in 1989, early season competition for water caused corn to yield less in the row bordering oat than in the row bordering soybean. Comparative soybean yields in border and center rows also depended on rainfall; with adequate water, soybean yield next to the oat strip was greater than or equal to yield in the center of the strip. Oat border rows yielded higher than those in the oat strip center. Timing differences in crop life cycles and water availability seem to influence how these crop species interact, particularly at the border positions. Overall, the strip intercropping system seems a suitable alternative to current practices.

Corn-Soybean and Alternative Cropping Systems Effects on NO 3 -N Leaching Losses in Subsurface Drainage Water

Alternative cropping systems can improve resource use efficiency, increase corn grain yield, and help in reducing negative impacts on the environment. A 6-yr (1993 to 1998) field study was conducted at the Iowa State University’s Northeastern Research Center near Nashua, Iowa, to evaluate the effects of non-traditional cropping systems [strip inter cropping (STR)-corn (Zea mays L.)/soybean (Glycine max L.)/oats (Avina sativa L.)]; alfalfa rotation (ROT)-3-yr (1993 to 1995) alfalfa (Medicago sativa L.) followed by corn in 1996, soybean in 1997, and oats in 1998), and traditional cropping system (corn after soybean (CS) and soybean after corn (SC) on the flow weighted average nitrate-nitrogen (NO3-N) concentrations and NO3-N leaching losses with subsurface drainage water. The soils at the research site are loamy with 3% to 4% organic matter and are underlain by subsurface drainage system. The data collected from four experimental treatments were analyzed as an unbalanced incomplete block design using F-test and T-test among treatments and within treatments, respectively. When averaged across 6-yr, non-traditional cropping systems reduced flow weighted average NO3-N concentrations in subsurface drain water with highly significantly effect (P < 0.01) in comparison with traditional cropping system (6.5 vs. 11.2 mg L-1). Similarly, the strip inter cropping system increased corn grain yields by 5% (9.03 vs. 8.6 Mg ha-1) and reduced NO3-N leaching losses by 6% (12.6 vs. 13.5 kg-N ha-1) and showed no difference in soybean yields when compared with traditional cropping system. Results of the study indicate that strip inter cropping and alfalfa rotation systems have the potential to reduce NO3-N leaching into the shallow groundwater system and possibly can become one of the better sustainable farming systems in Midwestern agriculture.

Ridge tillage effects on simulated water and heat transport

Abstract Ridged soil surface configurations are often used as a management tool to improve the plant root environment. Possible benefits for ridge tillage systems include warmer and dryer seed-zone soil conditions in the spring, better control of wheel-traffic patterns, and better crop residue management for erosion control. This study compared soil physical properties in the plant row, the untracked interrow, and the wheel-tracked interrow positions for a ridge tillage system on three soils. Soil property information was used to model the effects of soil variability and ridge height on subsurface water and heat transport. Simulated water and heat flow in a ridge seemed to be different from that of a flat surface. Taller ridges had a greater influence on water and heat movement than shorter ridges. There seems to be an optimum ridge height for fastest warming and drying. Variable soil properties affected predicted soil temperature distributions less than predicted matric potential distributions. The compacted zone had a lower matric potential deep in the profile and a higher matric potential near the surface than the uncompacted zone.

Nutrient removal by prairie filter strips in agricultural landscapes

Nitrogen (N) and phosphorus (P) from agricultural landscapes have been identified as primary sources of excess nutrients in aquatic systems. The main objective of this study was to evaluate the effectiveness of prairie filter strips (PFS) in removing nutrients from cropland runoff in 12 small watersheds in central Iowa. Four treatments with PFS of different spatial coverage and distribution (No-PFS, 10% PFS, 10% PFS with strips, and 20% PFS with strips) were arranged in a balanced incomplete block design across four blocks in 2007. A no-tillage two-year corn (Zea mays L.) –soybean (Glycine max [L.] Merr.) rotation was grown in row-cropped areas beginning in 2007. Runoff was monitored by H flumes, and runoff water samples were collected during the growing seasons to determine concentrations of nitrate-nitrogen (NO3-N), total nitrogen (TN) and total phosphorus (TP) through 2011. Overall, the presence of PFS reduced mean annual NO3-N, TN, and TP concentrations by 35%, 73%, and 82%, respectively, and reduced annual NO3-N, TN, and TP losses by 67%, 84%, and 90%, respectively. However, the amount and distribution of PFS had no significant impact on runoff and nutrient yields. The findings suggest that utilization of PFS at the footslope position of annual row crop systems provides an effective approach to reducing nutrient loss in runoff from small agricultural watersheds.

Applying Ecological Principles to Land-Use Decision Making in Agricultural Watersheds

The use of ecological principles and guidelines in land-use planning, as advocated by the Ecological Society of America Committee on Land Use (Dale et al., Chapter 1) will be critically important to achieving sustainable ecosystems in the next few decades as the world’s human population continues to grow and land area under human management increases. Definition of these principles and articulation of guidelines for use by planners and decision makers is an important first step, but there are many obstacles to the application of ecological guidelines in the land-use planning process. The use of alternative future scenarios can help overcome some of the difficulties associated with application of ecologically healthy land-use practices in agricultural watersheds. With the future scenario approach, abstract goals such as enhancing water quality and restoring biological diversity are translated into specific land-use practices (wetland restoration, riparian buffers, alternative cropping practices, preserves) expected to help achieve these goals. Maps and Geographic Information Systems (GIS) databases of the future alternatives become the spatial data used to evaluate the responses of the various modeled endpoints as well as the response of human perceptions of changes in land use. Alternative futures can be used to frame landscape ecological hypotheses (cf. Ahern 1999); models can then be employed to test those hypotheses and focus additional research on components that are poorly understood.