The use of narrow row spacing for the different landscape positions of a field could punish maize (Zea mays L.) grain yield. Two experiments were conducted (2006/07 and 2007/08) at different landscape positions in the Inland Pampas of Argentina. Hybrid DK190MG was grown at the commonest plant density used at each landscape position (approximately 5.1 plants/m2 at the summit, 6.5 plants/m2 at shoulder-slope position, and 7.6 plants/m2 at foot-slope position) with three row spacings (0.38？m, 0.52？m, and 0.38？m in a skip-row pattern). At the silking stage of maize crops, soil water content (0–200？cm depth) and maximum light capture differed ( ) among landscape positions but were similar among row spacings. Differences in grain yield among landscape positions (mean 806, 893, and 1104？g/m2 at the summit, shoulder-slope position, and foot-slope position, resp.) were related to kernel number/m2 ( ), which was closely related ( ) to light capture around silking. Grain yield reductions (6 to 20%) were recorded when crops were cultivated in rows 0.38？m apart. The skip-row pattern did not improve grain yield. Maize grain yield was optimized in rows 0.52？m apart along the sandy landscape positions of the fields. 1. Introduction Maize (Zea mays, L.) production in Argentina was traditionally concentrated within the most productive sub-region of the Pampas, that is, the Rolling Pampas . This humid (approximately 950？mm/year) temperate (mean annual temperature of 16°C, frost-free period of 240 days) area has the least number of climatic constraints to agriculture in Argentina and the most fertile soils (i.e., Typic Argiudolls; ) of the Southern Hemisphere . Favorable international prices of agricultural commodities (http://www.fao.org/es/esc/prices) together with changes in climate trends; for example, increases in precipitation up to 50% in some areas of the Pampas , have promoted the expansion of annual crops into previously semiarid areas (less than 700？mm/year, mean annual temperature of 16°C and a frost-free period of 220 days); for example, to the west and southwest of the Rolling Pampas, the Inland Pampas , where grazed pasture was the dominant land use. Soils of this subregion of the Pampas are predominantly Entic and Typic Hapludolls, with few constraints on root growth but with low water storage capacity (less than 100？mm in the first 1？m of the profile versus 170？mm of Typic Argiudolls) . However, depth of groundwater in the sandy landscapes of this region varies from <1？m (at foot-slope positions) to >4？m (at the summit) over distances
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