Increased Dryland Cropping Intensity with No-Till Barley

for increasing cropping intensity, improving soil quality, and controlling erosion in the conventional fallow areas For most of a century, the wide spread practice of growing only (Papendick, 1998). However, research with spring crops, one crop every other year in a tillage-based wheat (Triticum aestivum L.)–fallow rotation has degraded soils and contributed to environmenand in particular with no-till in the dry areas of the tal problems in low-precipitation (,350 mm annual) dryland regions inland Pacific Northwest, is limited. of the inland Pacific Northwest of the USA. Many growers in this Ciha (1983), in studies with annual spring wheat over 2-million-ha cropland area are increasing the intensity of cropping four years and at two low-precipitation (240 and 305 with spring crops, but most use conventional tillage (CT) for seedbed annual) sites in eastern Washington, reported that fall preparation. The agronomic performance of spring barley (Hordeum chiseling plus light spring tillage consistently produced vulgare L.), sown into CT seedbeds with double-disk drills or into higher yields than from spring tillage alone or no-till. standing stubble with several types of no-till (NT) drills (hoe, single This study showed that, even with the best yields, the disk, and notched coulter), was determined in two experiments conannual spring wheat was not competitive on an ecoducted both in 1996 and 1997 where the previous crop was either nomic basis with conventional winter wheat–fallow, bewinter wheat or spring barley. We measured stand establishment, seed-zone temperature, soil water, dry biomass accumulation, rhizoccause grain yields were not sufficient to offset increased tonia root rot, surface residue retention, and grain yield components. production costs with spring cropping unless winter anPlant stand (r 2 5 0.60), dry biomass accumulation (r 2 5 0.63), and nual grassy weeds were a major problem in winter spike density (r 2 5 0.62) as single independent variables, and comwheat. However, Ciha (1983) used a hoe drill with 360bined in a multiple regression model (R2 5 0.81), were strongly corremm row spacing, which is now considered excessively lated (P , 0.001) to grain yield. Early-season seed-zone temperatures wide for spring cereals. There has since been rapid dewere cooler under NT, but seed-zone water was slightly higher with velopment and improvement of (i) no-till drill technolCT. Low spike density consistently occurred in a wide row spacing ogy, (ii) higher-yielding spring cereal cultivars, (iii) (406 mm) NT drill treatment, and the highest overall yields were effective and affordable herbicides, and (iv) the underobtained with NT drills with rows spaced 255 mm or less. Rhizoctonia standing for timely and effective elimination of volunroot rot was severe on seminal roots in all treatments in three out of four trials, but did not appear to limit yields, possibly due to healthy teer cereals (green bridge) for root disease control. Furcrown roots and favorable growing conditions. No-till spring sowing thermore, research efforts to develop intensive and into undisturbed standing stubble (2420–5230 kg ha21) can produce diversified cropping systems using no-till in low-precipigrain yields equal to or exceeding those under CT and can provide tation dryland areas have been renewed (Schillinger et environmental and potential soil quality benefits for low-precipitation al., 1998; Young et al., 1998). dryland farming areas in the inland Pacific Northwest. Spring barley is another option with no-till spring sowing and is well adapted to the dry zones. One cropping sequence that has potential is winter wheat–spring F in the dryland areas of the Pacific Northbarley–fallow, or even barley for two years in a row, west (,350 mm annual precipitation) has been with the barley no-tilled into the crop stubble. Minimum mostly an intensive tillage-based wheat–fallow system or delayed minimum tillage fallow or chemical fallow since the land was broken out of native grassland and practices can be applied after the barley crop, which sage in the 1880s. Tillage is well known to accelerate provides a management option with a high potential for the loss of soil organic matter by increasing biological erosion control for the spring cropping system. oxidation and often by increasing soil erosion. The loss Rhizoctonia root rot [caused by Rhizoctonia solani is exacerbated with fallow, because oxidation of carbon (Kühn) AG8] is the most important disease of spring exceeds carbon input from crop residues during the twobarley sown directly into cereal stubble under Pacific year cycle (Rasmussen and Parton, 1994). Because of Northwest conditions (Ogoshi et al., 1990; Pumphrey et the decline in organic matter and associated soil quality, al., 1987; Weller et al., 1986). This is ordinarily a minor most tillage-based farming systems in dryland environdisease of wheat and barley grown with conventional ments are not sustainable in the long term (Papendick tillage, but it can be devastating on these crops in noand Parr, 1997). Options for maintaining and improving till cropping systems (Smiley et al., 1992), as has also soil quality in the drylands are to simultaneously inbeen seen in Australia (Rovira, 1986). The two most crease the cropping intensity and reduce or eliminate effective practices shown to limit the severity of this tillage. The use of spring cropping in combination with disease in no-till cropping systems are (i) elimination no-till sowing would appear to offer the best approach of volunteer and other grass hosts of the pathogen 2 to 3 wk and preferably 2 to 3 mo before sowing the barley Dep. of Crop and Soil Sciences, Dep. of Plant Pathology, and USDAor wheat (Smiley et al., 1992), and (ii) soil disturbance ARS, 201 Johnson Hall, Washington State Univ., Pullman, WA 99164in the seed row 50 to 60 mm below the seed at the time 6420. Washington State Univ. Crop and Soil Sciences Dep. Technical of sowing (Roget et al., 1996). Paper no. 9911-15. Received 14 Dec. 1998. *Corresponding author