Joseph L. Pikul

Water infiltration and storage affected by subsoiling and subsequent tillage

and prone to soil compaction (Busscher et al., 1986; Sojka et al., 1990). These loamy sands are easily comBenefits of subsoiling are difficult to predict. Objectives were to pacted when exposed to traffic or other consolidation (i) determine effect of subsoiling on water infiltration and storage and (ii) evaluate longevity of tillage-induced soil structure. Experiforces. Clay loams of the Southern Great Plains (Unger, ments were conducted during two years and on two soils that were 1993a) have dense Bt1 and Bt2 horizons that limit water not subsoiled (NoSS), subsoiled (SS), and subsoiled plus secondary infiltration and plant root penetration. Silt loams of the tillage (SSplus). Soils were Dooley fine sandy loam and Williams Pacific Northwest frequently have shallow layers of high loam (fine-loamy, mixed, superactive, frigid Typic Argiustolls) near strength that have been implicated as the cause of reCulbertson, MT. Subsoiling, to a depth of 0.3 m, in Exp. 1 was with duced water infiltration (Pikul et al., 1990) and poor a paratill and with parabolic shanks in Exp. 2. Secondary tillage was plant performance (Sojka et al., 1993). Repeated shalwith a disk in Exp. 1 and with sweeps in Exp. 2. Infiltration was low tillage of sandy loam soils in eastern Montana has measured using a sprinkler infiltrometer. Final infiltration rate, after elevated bulk density ( b) and PR at a depth of 10 cm two simulated storms, was 14 mm h 1 on NoSS, 29 mm h 1 on SS, (Pikul and Aase, 1995). These pans are commonly reand 7 mm h 1 on SSplus. Penetration resistance (PR) measurements suggest that soil subsidence following simulated rainstorms was less ferred to as tillage pans and are a consequence of preson treatments with no secondary tillage. Average water drainage from sure applied by normal tillage operations. The cases the 1.83-m profile was 1.4 mm h 1 during the first 3 d after water cited are but a small sample of typical pans that are application. Average drainage was 0.23 mm h 1 during Days 3 to 7 mentioned in the literature. In each case, the cause of and 0.09 mm h 1 during Days 7 to 15. Regardless of improved water the pan and the climate were different, but tillage was infiltration under SS, all soil profiles (1.83 m deep) drained to ≈444 mm sought as the means to loosen the pan and improve of water in 15 d. Results reveal a difficult soil management problem. water relations and crop performance. Subsoiling initially improves infiltration, but no additional water storObjectives were to (i) determine effect of subsoiling age was discernable after 15 d. Further, excess water percolation has on water infiltration and storage and (ii) evaluate lonpotential to leach nitrate-N from the profile. gevity of soil structure created by tillage following three wetting and draining cycles. W limits crop production in the semiarid MATERIALS AND METHODS northern Great Plains of the USA. To successfully grow a crop every year it is essential to limit evaporative Experimental Site loss of water and maximize soil water storage. Water Water infiltration experiments were conducted on a 32-ha conservation measures are important for successful anresearch farm located 11 km north of Culbertson, MT, USA. nual cropping on the semiarid northern Great Plains Experiment 1 was within a Dooley fine sandy loam (fineand, with careful management of soil and crops; continuloamy, mixed, superactive, frigid Typic Argiustolls) mapping ous annual small grain production can be successful unit. Experiment 2 was within a Williams loam (fine-loamy, (Aase and Pikul, 1995; Aase and Schaefer, 1996). Summixed, superactive, frigid Typic Argiustolls) mapping unit. mer fallow is commonly practiced to store water in the Dooley and Williams soils are geographically associated. The soil for use by a later crop (Haas et al., 1974). However, Williams series consists of very deep, well drained, moderately a high evaporation rate makes summer fallowing ineffislow or slowly permeable soils formed in calcareous glacial till. Williams soils are found on glacial till plains and moraines cient in storing water (Tanaka, 1985; Tanaka and Aase, and have clay loam B2t horizons. The Dooley series consists 1987). Additionally, the fallow–wheat (Triticum aestiof very deep, well-drained soils that formed in alluvium or vum L.) crop sequence has been implicated as the cause eolian material 0.5 to 1 m deep over glacial till or lacustrine of serious declines in soil C (Rasmussen and Parton, deposits. Dooley soils are on uplands and lacustrine areas and 1994). Thus, careful management of soil and crops are have sandy clay loam Bt horizons. In either case, below 0.3 m, key to efficient use of precipitation and maintenance of considerable textural heterogeneity is typical (Aase and Pikul, soil productivity. 2000). For example, within a 1.2-ha parcel, mapped as Dooley Shallow soil pans can impede water and gas movefine sandy loam, Pikul and Aase (1998) reported soil textures ment. Occurrence of pans may be a consequence of soil of sandy loam, sandy clay, and sandy clay loam at the 0.3to type or management or both. Many soils of the South0.6-m depth. Annual precipitation at the research site was 357 mm, with eastern Coastal Plain of the USA are weakly structured ≈283 mm (80%) occurring during April through September. Plots were laid out on portions of the farm that had been J.L. Pikul, Jr., USDA-ARS, Northern Grain Insects Research Laboramanaged in a fallow–wheat cropping sequence since about tory, 2923 Medary Ave., Brookings, SD 57006; J.K. Aase, USDAARS, Northwest Irrigation and Soils Research Laboratory, 3793 N. Abbreviations: v, soil water measurements; b, soil bulk density; NoSS, 3600 E., Kimberly, ID 83341, USA. Recieved 1 Apr. 2002. *Correnot subsoiled; SS, subsoiled; SSplus, subsoiled plus secondary tillage; sponding author (jpikul@ngirl.ars.usda.gov). PR, soil penetration resistance; SSI, soil subsidence index; SSR, soil strength response. Published in Soil Sci. Soc. Am. J. 67:859–866 (2003).

Soil properties and crop yield among four tillage systems in a wheat-pea rotation☆

Tillage systems that address soil conservation and sustainable crop yield need to be developed. Research was conducted on a Walla Walla silt loam (Typic Haploxeroll) to determine the long-term (19 years) effect of four tillage systems on soil properties and crop yield in a green pea (Pisum sativum L.)—winter wheat (Triticum aestivum L.) rotation that was started in 1968. The experimental design was a split plot with four replications. Wheat and peas were grown each season. The primary tillage systems were: (T1) fall moldboard plow after wheat and after peas (control); (T2) fall rototill after wheat and fall sweep after peas; (T3) spring moldboard plow after wheat and fall moldboard plow after peas; (T4) no tillage after wheat and fall sweep after peas. Soil measurements included bulk density, pH, organic carbon, penetration resistance, and saturated hydraulic conductivity. Profiles of bulk density, penetration resistance and pH revealed unique differences among treatments. However, there were no consistent differences in yield among the four tillage systems, in either green peas or wheat. From a crop production viewpoint, changes in soil properties on these tillage plots were inconsequential. From a soil erosion viewpoint, spring plowing (T3) and conservation tillage (T4) have an advantage over T2 and T1 because surface cover is maintained during the first winter following wheat harvest. Results show the importance of testing tillage systems over long periods of time and that the traditional system of fall moldboard plowing after wheat and after peas can be replaced by conservation systems without yield loss.

Economic risk, returns and input use under ridge and conventional tillage in the northern Corn Belt, USA.

Ridge tillage (RT) has been proposed as an economically viable conservation tillage alternative for row crop production; however the long-term economic viability of RT in the northern Corn Belt of the USA is largely unknown. Economic returns, risk and input use were compared for RT and conventional tillage (CT) in a corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation with high, medium and low nitrogen treatments. The analysis was based on 10 years of experimental data from Brookings, SD on a Barnes clay loam (US soil taxonomy: fine-loamy, mixed, superactive, frigid Calcic Hapludoll; FAO classification: Chernozem). Economic returns were significantly higher at the highest nitrogen treatment levels. Highest average net returns to land and management were

Water Use and Biomass Production of Oat–Pea Hay and Lentil in a Semiarid Climate

78 per hectare for RT at the high nitrogen treatment level (RT-H) followed by

Nitrogen Use and Carbon Sequestered by Corn Rotations in the Northern Corn Belt, U.S.

59 per hectare for CT at the high nitrogen treatment level (CT-H). Risk, measured as the standard deviation of net returns, was the lowest for CT at the medium nitrogen treatment level (CT-M) followed by RT-H and CT-H. However, net returns were substantially lower under CT-M at

Hayland conversion to wheat production in semiarid eastern Montana: tillage, yield and hay production comparisons

32 per hectare. Average yields and average operating costs were not significantly different for RT-H and CT-H. Reduced equipment operating costs for CT-H were offset by increased herbicide costs for RT-H. Equipment ownership costs were significantly lower for RT-H than CT-H. There were no significant differences in fertilizer use for RT and CT. Pesticide use was significantly higher for RT-H than CT-H. Fuel use was 18-22% lower and labor use was 24-27% lower for RT-H than CT-H. Despite continued low adoption rates for RT in the northern Corn Belt, our analysis shows that RT is an economically viable alternative to CT.

Soil nitrogen mineralization influenced by crop rotation and nitrogen fertilization.

Zentner et al., 2001). Johnson (1982) found that income variability was reduced under summer fallow and that Suitability of alternative crops in the northern Great Plains remains summer fallow maximized return to land at low yields, a question because of water limitations. Objectives were to compare water use of an oat (Avena sativa L.)–pea (Pisum sativum L.) mix low wheat prices, and high N prices. grown for hay (OPH) to that of black lentil (Lens culinaris Medikus Progress in crop breeding and management coupled cv. Indianhead) grown as green manure (BL). Water use and plant with desire to improve economic advantages of crop biomass for OPH and BL were measured near Culbertson, MT (Site rotations have resulted in attempts to establish new 1), during 4 yr. Soil water was measured by neutron attenuation. rotations in traditional fallow–grain production areas Precision-weighing lysimeters were used at Site 2, located 65 km (Campbell et al., 2002). Legumes have historically been southeast of Site 1, to measure water use. Soil was a Williams loam included in crop rotations. Concern over loss of soil (fine-loamy, mixed, superactive, frigid Typic Argiustolls). Biomass of organic matter and cost of fertilizer N prompted a rediscrops was measured biweekly. Relative feed value (RFV) based on covery of green-manure crops for semiarid wheat promeasured neutral detergent fiber and acid detergent fiber was calcuduction systems even in light of the literature base that lated. Biomass under OPH was 34 and 46% greater than with BL at Sites 1 and 2, respectively. At Site 1, biomass accumulated at a rate suggested green-manure farming systems were not profof 14 kg ha 1 mm 1 water used under BL and 23 kg ha 1 mm 1 under itable in the Dakotas and Canadian Prairie Provinces OPH. Biomass accumulated at a rate of 21 kg ha 1 mm 1 under BL (Pieters, 1917). Conclusions from studies started in and 29 kg ha 1 mm 1 under OPH at Site 2. Hay RFV, at full bloom Montana in the early 1900’s and reported after 28and in pea, averaged 116 (Number 2 hay), and this did not change apprecia43-yr periods (Army and Hide, 1959) were similar to the bly as the crop matured to soft dough stage in oat. Oat–pea hay fits conclusions drawn by Pieters (1917). However, recent the growing conditions in the northern Great Plains and meets the studies on the Canadian Prairies show that annual leneeds of producers for high quality hay. gumes have potential as green-manure crops (Rice et al., 1993). In grain lentil–wheat rotations, there has been a gradual reduction in fertilizer N requirement after W limits crop production in the semiarid northabout 6 yr (Campbell et al., 1992). Pikul et al. (1997) ern Great Plains, and consequently, cropping opconcluded that available N limited wheat production tions are limited. Wheat (Triticum aestivum L.) is the more than did soil water in rotations where green mamajor crop in Montana, accounting for nearly 58% of nure was the sole source of N. Black lentil has been all crop receipts in 2000 (Montana Agric. Stat. Serv., identified as having good potential as a green manure 2001). There were about 1.9 million ha of wheat (70% because of low seed cost, intermediate top growth, and spring wheat) in Montana in 2000, all being nonirrigated. N yield (Townley-Smith et al., 1993). Nearly 70% of that wheat was produced on land followSuitability of alternative crops and rotations in the ing fallow. Because of climatic, economic, or cultural traditional semiarid wheat production areas remains a constraints, summer fallow is still a common practice. question. Annual legume species have different N fixaFallow has accelerated soil C loss (Rasmussen and Partion capabilities and water use efficiencies. Biederbeck ton, 1994; Aase and Pikul, 1995), soil erosion (especially and Bouman (1994) tested water use characteristics of where there are meager amounts of crop residue cover), BL, Tangier flat pea (Lathyrus tingitanus L.), chickling and development of saline seeps (Black et al., 1981). vetch (Lathyrus sativus L.), and feed pea. Annual leSoil water storage efficiency of fallow ranges from about gumes that produce high quantities of phytomass had 15 to 40% (Black and Power, 1965; Tanaka and Aase, water use efficiencies that were greater than legume 1987; Peterson et al., 1996). However, even with low species that produced less phytomass. Feed pea and water-storage efficiency, rotations that included fallow chickling vetch used water more efficiently than other were found to have the lowest level of financial risk legumes tested. Green manure may ultimately improve soil condition; however, costs associated with this pracJ.L. Pikul, Jr., USDA-ARS, Northern Grain Insects Res. Lab., 2923 Medary Ave., Brookings, SD 57006; J.K. Aase (retired), USDA-ARS, Abbreviations: ADF, acid detergent fiber; BL, black lentil grown as Northwest Irrig. and Soils Res. Lab., 3793 N. 3600 E., Kimberly, a green manure; CV, coefficient of variation; ET, evapotranspiration; ID 83341; and V.L. Cochran (retired), USDA-ARS, Northern Plains GDD, growing degree days; NDF, neutral detergent fiber; OPH, oat– Agric. Res. Lab., 1500 N. Central Ave., Sidney, MT 59270. Mention pea mix grown for hay; RFV, relative feed value; SW–BLc, spring of trade names is for the benefit of the reader and does not constitute wheat–black lentil rotation where black lentil was terminated by chemiendorsement by the USDA over other products not mentioned. Recal; SW–BLd, spring wheat–black lentil rotation where black lentil was ceived 23 Apr. 2003. *Corresponding author (jpikul@ngirl.ars.usda.gov). terminated by disking; SW–CF, 2-yr rotation of spring wheat–chemical fallow (no tillage during fallow); SW–OPH, 4-yr rotation of spring Published in Agron. J. 96:298–304 (2004).  American Society of Agronomy wheat–buckwheat–fallow–oat/pea mix grown for hay; WW–OPH, 4-yr rotation of winter wheat–buckwheat–fallow–oat/pea mix grown for hay. 677 S. Segoe Rd., Madison, WI 53711 USA

Crop and Soil Response to Long-Term Tillage Practices in the Northern Great Plains

Diversified crop rotation may improve production efficiency, reduce fertilizer nitrogen (N) requirements for corn (Zea mays L.), and increase soil carbon (C) storage. Objectives were to determine effect of rotation and fertilizer N on soil C sequestration and N use. An experiment was started in 1990 on a Barnes clay loam (U.S. soil taxonomy: fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, SD. Tillage systems for corn–soybean (Glycine max [L.] Merr.) rotations were conventional tillage (CS) and ridge tillage (CSr). Rotations under conventional tillage were continuous corn (CC), and a 4-year rotation of corn–soybean–wheat (Triticum aestivum L.) companion-seeded with alfalfa (Medicago sativa L.)–alfalfa hay (CSWA). Additional treatments included plots of perennial warm season, cool season, and mixtures of warm and cool season grasses. N treatments for corn were corn fertilized for a grain yield of 8.5 Mg ha (highN), of 5.3 Mg ha (midN), and with no N fertilizer (noN). Total (1990–2000) corn grain yield was not different among rotations at 80.8 Mg ha under highN. Corn yield differences among rotations increased with decreased fertilizer N. Total (1990–2000) corn yields with noN fertilizer were 69 Mg ha under CSWA, 53 Mg ha under CS, and 35 Mg ha under CC. Total N attributed to rotations (noN treatments) was 0.68 Mg ha under CSWA, 0.61 Mg ha under CS, and 0.28 Mg ha under CC. Plant carbon return depended on rotation and N. In the past 10 years, total C returned from above- ground biomass was 29.8 Mg ha under CC with highN, and 12.8 Mg ha under CSWA with noN. Soil C in the top 15 cm significantly increased (0.7 g kg) with perennial grass cover, remained unchanged under CSr, and decreased (1.7 g kg) under CC, CS, and CSWA. C to N ratio significantly narrowed (–0.75) with CSWA and widened (0.72) under grass. Diversified rotations have potential to increase N use efficiency and reduce fertilizer N input for corn. However, within a corn production system using conventional tillage and producing (averaged across rotation and N treatment) about 6.2-Mg ha corn grain per year, we found no gain in soil C after 10 years regardless of rotation.

Larval sampling and instar determination in field populations of northern and western corn rootworm (Coleoptera: Chrysomelidae)

Abstract When converting grass- and haylands to cultivated crop production, care must be taken to conserve and maintain soil resources while considering economic issues. Methods of breaking sod can have a bearing on erosivity, physical and chemical properties of soils, and cost of production. Our objective was to compare three methods of converting crested wheatgrass [ Agropyron desertorum (Fisch. ex Link) Schult.] hayland to wheat ( Triticum aestivum L.) production vs. leaving the land for hay production. We initiated a study in 1990 on Dooley sandy loam (fine-loamy, mixed Typic Argiboroll) near Froid in semiarid eastern Montana, USA. Plots, replicated three times, were 12- by 30-m oriented east to west on a north-facing slope. We converted sod to cultivated crop production by: (1) moldboard plow, (2) toolbar with sweeps, (3) herbicides (no-till). Plots were fallowed until spring 1991 and then seeded to spring wheat each of the next four years. All wheat plots were fertilized with 224 kg ha −1 of 18-46-0 in 1991 and 1992, and 34 kg ha −1 nitrogen as 34-0-0 in 1993 and 1994. Grass was either fertilized same as wheat or not fertilized. Wheat yields averaged 2540 kg ha −1 on tilled treatments and 2674 kg ha −1 on no-till. Fertilized grass consistently out-yielded unfertilized, and averaged 3.2 Mg ha −1 vs. 1.8 Mg ha −1 . Toolbar with sweeps had highest economic return of US

Corn Yield, Nitrogen Use, and Corn Rootworm Infestation of Rotations in the Northern Corn Belt

169.48 ha −1 to pay for land, labor, and management. Moldboard plow had US