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 farmer's 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.

A three‐crop strip intercropping system including corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and oat (Avena sativa L.) interseeded with nondormant alfalfa (Medicago sativa L.), was established in south‐central Iowa on a poorly drained Haig soil (fine, smectitic, mesic Vertic Argiaquoll). In 1989 (a dry year) and 1990 (a wet year), we studied the effect of tillage treatment (conventional, CT; reduced, RT; and no‐till, NT) and row position on soil water content, canopy and air temperatures, corn grain yield, and yield components. No‐till resulted in the most favorable soil water status, plant water status, and grain yield in 1989. No‐till had the poorest performance in 1990, mainly because of excessive soil water. The opposite was true for conventional till in both years. Reduced till yield equaled that for the most productive tillage treatment in both years. Conventional and reduced tillage resulted in lower corn grain yield at the border with oat‐alfalfa than with soybean because oat depleted soil water more than soybean in both years. In contrast, for no‐till the corn grain yield at the border with oat‐alfalfa was 6% greater than corn yield bordering soybean in 1989 and 13% greater in 1990. When water was not limiting, in 1990, both corn borders outyielded the center rows by an average of 14% in NT, 27% in RT, and 28% in CT. Soil water content rankings throughout the 1989 season were NT > RT > CT and row position rankings were soybean border > center > oats‐alfalfa border. In 1990, there were no soil water content differences between tillage treatments and row positions. Reduced tillage is the most suitable soil management system for corn production with three‐crop strip intercropping on this soil, considering consistently high relative yields for both wet and dry years.

IV RESUMO Os objetivos deste trabalho foram determinar e modelar o escoamento superficial para solos com diferentes características físicas a partir de diferentes intensidades de chuva. Foram realizadas chuvas simuladas em diferentes solos

Abstract. Humanity depends on the existence of healthy soils, both for the production of food and for ensuring a healthy, biodiverse environment, among other functions. COVID-19 is threatening food availability in many places of the world due to the disruption of food chains, lack of workforce, closed borders and national lockdowns. As a consequence, more emphasis is being placed on local food production, which may lead to more intensive cultivation of vulnerable areas and to soil degradation. In order to increase the resilience of populations facing this pandemic and future global crises, transitioning to a paradigm that relies more heavily on local food production on soils that are carefully tended and protected through sustainable management is necessary. To reach this goal, the Intergovernmental Technical Panel on Soils (ITPS) of the Food and Agriculture Organization of the United Nations (FAO) recommends five active strategies: improved access to land, sound land use planning, sustainable soil management, enhanced research, and investments in education and extension. The soil is the great connector of lives, the source and destination of all. It is the healer and restorer and resurrector, by which disease passes into health, age into youth, death into life. Without proper care for it we can have no community, because without proper care for it we can have no life. – Wendell Berry (American novelist)

Corn (Zea mays L.) has greater yield potential when strip‐intercropped than when monocropped, but this potential may be compromised by a failure to understand how N requirements change with row position and the possible N competition of adjacent crops. A four block, completely randomized, split‐plot experiment was conducted on a Haig loam soil (fine, smectitic, mesic Vertic Argiaquolls) in southern Iowa, to determine crop utilization of N fertilizer pointinjected into corn rows. Nitrogen fertilizer uptake was evaluated in (i) corn rows injected with labeled N fertilizer; (ii) corn rows adjacent to the injected rows; and (iii) plants at the edge of the adjacent soybean [Glycine max (L.) Merr.] and oat (Avena sativa L.)‐alfalfa (Medicago saliva L.) strips. Main treatments consisted of three tillage systems: conventional tillage (CT), reduced tillage (RT), and no‐till (NT). Subplot treatments consisted of point injection of l5N‐enriched NH4NO3 (67 kg N ha−1) in‐row at three row positions within the corn strips. Grain and stover yield, Kjeldahl N, and isotope composition of plant materials were determined. Corn yield and labeled‐N recovery differed with tillage to the extent that tillage affected early and total season moisture availability. Labeled‐N recovery in labeled rows did not differ with row position. Labeled‐N recovery in unlabeled rows or crop borders was typically less than 5% of that recovered by labeled rows. Nitrogen is primarily recovered by the row to which it is applied; therefore, row‐by‐row precision applications seem to be an appropriate management tool.