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1999 STEEP III Final ReportTITLE: Impact of long-term
no till on soil physical, chemical, and microbial properties INVESTIGATORS: David Bezdicek1, John Hammel2, Mary Fauci1, Dennis Roe3, and Jon Mathison2 1WSU, 2UI, and 3NRCS INTERIM REPORT:
OBJECTIVES:
KEY WORDS: no-till, tillage, soil quality, crop productivity STATEMENT OF PROBLEM: No till (NT) agriculture presents some unique opportunities for reducing wind and water erosion and for improving crop productivity and economic returns. Higher surface residue in NT hinders planting, yet is essential for control of wind and water erosion. Heavy NT drills may compact the soil. Crop yield potential can increase through more efficient use of soil moisture, and thus can expand cropping options to the high and intermediate rainfall areas by allowing for more spring-grown crops. Reduction in tillage can increase soil organic matter and thereby increase soil quality. Many producers and researchers believe that soil quality improves under NT, but long-term documentation is needed. Our goal is to document changes in soil quality attributed to NT agriculture. We have evaluated soil physical, chemical, and biological properties in cooperating grower fields in NT operation for 10 to 25 years in comparison to adjacent conventional practices. ZONE OF INTEREST: This study is conducted in the, high, intermediate, and low rainfall zones. ABSTRACT OF RESEARCH FINDINGS: Soil physical, chemical, and biological properties for five cooperating grower fields and one research plot in direct seed for 10 to 25 years were compared to adjacent conventional tillage practices in 1997. Soil organic matter, microbial activity, soil N release, and soil test P and K tended to be higher at all sites under direct seeding compared to conventional tillage. The greatest increase in soil organic matter of 50% was noted at Palouse, WA under 25 years of direct seeding. Fewer significant differences were noted at the drier sites due to the accumulation of less soil organic matter. Soil under direct seed was more compact, with higher bulk densities and greater penetration resistance. However they tended to have greater water infiltration. We propose that there is a change in soil pore size distribution after years of direct seeding, resulting in larger soil pores from undisturbed old root channels and earthworm channels. Winter soil water storage and water consumption by crops grown under direct seed and conventional tillage tended to be the same in 1998. However water use efficiency was greater for direct seeded winter wheat in the annual rainfall area. Greater water use efficiency was also noted for spring barley grown under direct seed compared to spring wheat in the wheat-fallow rainfall zone. Maintaining surface cover in annual cropping and eliminating fallow are key reasons for the improved water use efficiency. The calibration of the Cropsyst model to no-till and conventional cropping systems at Palouse and Touchet allows us to utilize the Cropsyst model to predict future scenarios of these crops under different management systems. RESULTS AND INTERPRETATION: We continued to follow soil quality changes attributed to no-till (NT) agriculture in three agroclimatic zones in eastern Washington and northern Idaho was evaluated by assessing soil physical, chemical, and biological properties of long-term NT fields (Table 1) Most of the field results were reported in the 1997 and 1998 STEEP III reports. A summary of these results show that soil organic matter, microbial activity, soil N release, and soil test P and K were higher at all sites under DS compared to conventional tillage. The greatest increase in soil organic matter of 50% was noted at Palouse, with a slight increase noted at the wheat-fallow site at Touchet. Many of the above measurements were highest for direct seed compared to conventional at the soil surface 0-5 cm (0-2 inches), but were lower at the 5-20 cm depth due to the lack of surface soil inversion. Water infiltration into soil is often increased under direct seed because surface residues facilitate infiltration into the soil, although the soil may be more compact due to heavy equipment traffic. Bulk density at the annual cropping site in Palouse and the wheat-fallow site in Touchet were generally higher under direct seed than conventional and ponded infiltration of water shows that water entry is generally higher under DS than under conventional tillage (1998 STEEP Report). Surface impedance was generally higher under DS at the Palouse and Colfax that likely reflects the heavy no till drills used (1997 STEEP Report). We propose that direct seed systems may be more compact just below the soil surface, but that water infiltration may actually be enhanced due to the different soil pore size distribution. Under direct seed conditions, we propose that old root channels and earthworm channels are maintained from the lack of disturbance that facilitates infiltration of water through more macro pores. How this affects water and nutrient movement should be studied as water movement and leaching of nutrients may be facilitated through macro pores. In late 1997, weather stations were set up as part of Juan Pablo Fuentes's M.S work at the Palouse and Touchet sites (Table 1) to study winter soil water storage, seasonal changes in soil profile temperature and moisture, crop water use efficiency. We monitored continuously for soil moisture at 30-cm (1 ft) intervals to 150 cm (5ft) using time domain refractrometry (TDR). The weather stations monitored total radiation, wind speed, air temperature, and soil temperature (seed zone at 5-cm depth). Data were stored in storage modules, down loaded into a lap top computer, and assembled into one of several models to estimate crop water use efficiency. Soil nitrogen (ammonium and nitrate) was measured at monthly intervals to determine crop N use efficiency. Our results show that surface residues increased the water infiltration rate and suggest that there is greater potential for more storage of water under DS. Seasonal soil temperature was consistently lower for no-till than conventional at Palouse in 1998 (1998 STEEP Report). Surface resides under direct seed maintained lower soil temperature as would be expected. Total precipitation, total water consumed, crop yield, and crop water use efficiency for winter wheat at Palouse in 1998 is shown in Table 2. Excellent yields were noted for both the direct seed and conventional fields. However, water use efficiency was higher under direct seed due to the higher yield obtained. Total water consumed was similar. Total precipitation, total water consumed, crop yield, and water use efficiency for direct seed spring barley and conventional spring wheat is shown in Table 2. Water use efficiency was higher under direct seed compared to conventional. Spring wheat was grown continuously for 14 years at the direct seed site, but replaced with spring barley in 1998. Winter wheat is normally rotated with fallow in conventional system, but was replaced with spring wheat in 1998. The Cropsyst model was calibrated for winter wheat growth for both tillage systems in Palouse. The calibration of winter wheat, found the most important modeling parameters belong to the morphological and physiological aspects of plants such as leaf area index, leaf stem partition, and days degrees required for vernalization. During 30 years of simulation, direct seed had more variability in the above ground biomass than the conventional situation. This behavior is mainly explained by higher yield in the calibration of winter wheat under direct seed. Given the approximation of growth yields to a normal distribution, yield seems to be mainly influenced by the climatic conditions simulated.
Table 2. Fall 1997-1998 total precipitation, total water consumed, crop yield, and crop water use efficiency (WUE) under conventional and DS systems.
COOPERATORS: Jim Cook, USDA-ARS Plant Pathology: Provide access to USDA long-term plots and collaborate in interpretation of data Tim Fiez, WSU Cooperative
Extension: Collaborate on direct seeding research Roger Veseth, WSU
and UI Cooperative Extension: Assist in site selection and collaborate
in research David Huggins, USDA-ARS:
Collaborate on interpretation of data and statistical analysis Steve Albrecht USDA-ARS:
Collaborate on research PUBLICATIONS AND PRESENTATIONS (current year): Juan Pablo Fuentes, David Bezdicek, John Hammel, Mary Fauci, Dennis Roe and Jon Mathison. Impact of Direct Seeding on Crop Water Use Efficiency, Soil Physical Properties and Soil Quality. Northwest Direct Seed Cropping Systems Conference and Trade Show, Jan. 5-7, 1999, Spokane WA. David Bezdicek. Soil pH, Trends and Implications for Direct Seeding. WSU/USDA Field Day, Pullman, WA, July 8, 1999. David Bezdicek, Juan Pablo Fuentes, John Hammel, Mary Fauci, Dennis Roe, and Jon Mathison. Impact of Long-Term Direct Seeding on Soil Quality. In 1999 Field Day Proceedings: Highlights of Research Progress, WSU Technical Report 99-1. David Bezdicek, Juan Pablo Fuentes, John Hammel, Mary Fauci, Dennis Roe, and Jon Mathison. Impact Of Long-Term Direct Seeding On Soil Physical, Chemical, And Microbial Properties And Crop Water Use Efficiency In Washington State, USA. XIV Congreso Latinoamericano De La Ciencia Del Suelo, Temuco Chile, Nov. 1999 Juan Pablo Fuentes. Fate of Soil Water and Nitrogen in Dryland No-till and Conventional Cropping Systems in Washington State. WSU seminar, Dec. 7, 1999. ACKNOWLEDGEMENTS:
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