Change in Physical Properties of “Terra Rossa” Soils in Paraguay under No‐tillage

Abstract

maintain constant soil temperatures (Benegas, 1998), and improve soil structure and water infiltration rates The introduction of no-tillage farming stabilized soybean [Glycine (Gill, 1998). On the other hand, some studies indicated max. (L.) Merr.] yields on "Terra Rossa" soils of eastern Paraguay at a yield level that is among the highest in the world. The objective that long-term no-tillage farming might also cause sevof this study was to clarify the effect of long-term no-tillage in a eral problems. These are accumulation of applied nutrisoybean-based farming system on physical properties of "Terra ents in the surface soil (Seki et al., 2001; Pierce et al., Rossa" soils with different texture. Four farmers' fields of different 1994), high bulk density (Benegas, 1998; Betz et al., soil texture were studied in 1990 and 2000. Two fields had fine-textured 1998; Pierce et al., 1994), low water permeability (Besoil and other two had coarse-textured soil. A 1-m deep pit was negas, 1998), and high soil penetration resistance (Betz prepared at each site at the exact same location in 1990 and 2000,

Water ‘on the rocks’: a summer drink for thirsty trees?

“…S1) (Zwieniecki & Newton, 1995), but rock‐to‐root water transfer is likely to be limited by rock hydraulic conductivity. Different types of carbonate rocks have hydraulic conductivities in the range 10 −9 –10 −12 m s −1 (Boving & Grathwohl, 2001; Pulido‐Bosch et al ., 2004), that is, several magnitudes lower than values reported for clayey soils (10 −5 –10 −9 m s −1 ), such as those dominating karstic areas (Kubota et al ., 2005; Bhardwaj et al ., 2007). Mycorrhizas might improve water transfer to the roots (Nardini et al ., 2000; Bornyasz et al ., 2005; Lehto & Zwiazek, 2011), but rock hydraulics would probably remain limiting.…”

Effect of fertilizer-N application and seed coating with rhizobial inoculants on soybean yield in eastern Paraguay

“…A no-tillage farming system was used for both crops. Under continuous no-till system, the bulk density and penetration resistance in "Terra Rossa" soils tend to increase (Kubota et al, 2005a). With high soil compaction it is possible that N fixation is reduced by insufficient oxygen supply to soybean roots and nodules (Voorhees et al, 1976).…”