Modeling tillage effects on soybean growth and yield

The effects of tillage and cooler soil temperatures under surface residue were incorporated into CROPGRO-Soybean. An energy balance-based soil temperature model was integrated into CROPGRO-Soybean and compared to the original soil temperature model, which is driven primarily by air temperature. The new model gave an 8.6% higher R2 (0.88 and 0.81 for new and old models, respectively) and 20.6% lower RMSE at 10 cm depth (2.7°C and 3.4°C for new and old models, respectively) under bare soil conditions for 5 years of validation. The new model generally gave lower RMSE and higher R2 values compared to the old model at all soil depths. It gave excellent predictions of emergence under Central Iowa conditions, with an average error of 0.6 day for 8 planting dates in spring of 1997. The old model had an average error of 1 day. Under cool conditions, the new model gave better predictions of emergence dates. However, under warm periods, both models typically gave the same accuracy, and were within 1 day of the measured emergence date. A tillage component was integrated into CROPGRO-Soybean and tested for conditions at Ames, IA. Predictions of changes in soil physical properties were consistent with the literature. The model gave good predictions of soil temperature at 6 cm depth under moldboard (R2 = 0.81), chisel plow (R2 = 0.72), and no-till (R2 = 0.81) for 1997 and was able to simulate cooler soil temperatures under no-till in early spring and consequent delays in emergence. Excellent predictions of soybean phenology and biomass accumulation (e.g. R2 = 0.98, 0.97, and 0.95 for pod weight predictions under moldboard, chisel plow, and no-till, respectively) were obtained for 1997. Limited testing of the model for central and northeast Iowa conditions showed that slightly lower yields from no-till were primarily due to delayed emergence. Predicted yields from no-till were slightly higher when no-till had better water conservation (i.e. in drought years) and negligible delays in emergence. Generally, the tillage model confirmed field experiments showing that tillage did not significantly affect soybean yields in years with little or no water stress

Proceedings of the 23rd annual Central Plains irrigation conference

Presented at Proceedings of the 23rd annual Central Plains irrigation conference held in Burlington, Colorado on February 22-23, 2011.Includes bibliographical references.Irrigation water management practices could greatly benefit from using soil moisture sensors that accurately measure soil water content or potential. Therefore, an assessment on soil moisture sensor reading accuracy is important. In this study, a performance evaluation of selected sensor calibration was performed considering factory- laboratory- and field-based calibrations. The selected sensors included: the Digitized Time Domain Transmissometry (TDT, Acclima, Inc., Meridian, ID) which is a volumetric soil water content sensor, and a resistance-based soil water potential sensor (Watermark 200, Irrometer Company, Inc., Riverside, CA). Measured soil water content/potential values, on a sandy clay loam soil, were compared with corresponding values derived from gravimetric samples. Under laboratory and field conditions, the factory-based calibrations for the TDT sensor accurately measured volumetric soil water content. Therefore, the use of the TDT sensor for irrigation water management seems very promising. Laboratory tests indicated that a linear calibration for the TDT sensor and a logarithmic calibration for the watermark sensor improved the factory calibration. In the case of the watermark, a longer set of field data is needed to properly establish its accuracy and reliability

Navigating learning through catastrophic calamities: A phenomenological study

This study examined the lived experiences of technology and livelihood learners while navigating in the learning process despite the calamities like COVID-19 pandemic and typhoon Odette.  Data were gathered from in-depth interview with participants, focus group discussions, and key informant interview through the interview guide. Transcripts were analyzed using Colaizzi’s method, wherein meanings are formulated through sorted codes, categories, and themes.  Findings revealed three emerging themes on participants’ difficult and challenging experiences which include, uphill battles in learning, learning opportunities, and rise to the challenges.  Meanwhile, two themes were found for the underlying effects of these experiences including, role acceptance and psychosocial discomfort.  Furthermore, three themes were identified for learners’ responses to the challenges in learning process, including actions towards learning, coping amidst adversities, and pillars of strength.  These experiences provided concepts to educators to improve teaching and becoming flexible in designing lessons and learning tasks guided with the learning continuity model mainly designed to teach in the midst of crises. Hence, the Department of Education may spearhead community assessment while in curriculum development to suffice the needs of the learning community and may guide division and school offices in the implementation of their localized and contextualized learning continuity plans

Meeting irrigation demands in a water-challenged environment

Presented at Meeting irrigation demands in a water-challenged environment: SCADA and technology: tools to improve production: a USCID water management conference held on September 28 - October 1, 2010 in Fort Collins, Colorado.Includes bibliographical references.Accurate estimates of spatially distributed evapotranspiration (ET) using remote sensing inputs could help improve crop water management, the assessment of regional drought conditions, irrigation efficiency, ground water depletion, and the verification of the use of water rights over large irrigated areas. In this study, ET was mapped using surface reflectance and radiometric temperature images from the Landsat 5 satellite in a surface energy budget algorithm driven by a surface aerodynamic temperature (SAT_ET) model. The SAT_ET model was developed using surface temperature, horizontal wind speed, air temperature and crop biophysical characteristic measured over an irrigated alfalfa field in Southeastern Colorado. Estimates of the remote sensing-based ET for a 4.0 hectare alfalfa field and a 3.5 hectare oats field, during the 2009 cropping season, were evaluated using two monolithic weighing lysimeters located at the Colorado State University Arkansas Valley Research Center (AVRC) in Rocky Ford, Colorado. Although the overall model performance was encouraging, results indicated that the SAT_ET model performed well under dry atmospheric and soil conditions and less accurately under high air relative humidity and soil water content conditions. These findings are evidence that SAT_ET needs to be further developed to perform better under a range of environmental and atmospheric conditions

Elevated CO\u3csub\u3e2\u3c/sub\u3e further lengthens growing season under warming conditions

Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2—which can delay annual life cycle events—on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles

Incorporating field wind data to improve crop evapotranspiration parameterization in heterogeneous regions

Accurate parameterization of reference evapotranspiration ( ET0) is necessary for optimizing irrigation scheduling and avoiding costs associated with over-irrigation (water expense, loss of water productivity, energy costs, and pollution) or with under-irrigation (crop stress and suboptimal yields or quality). ET0 is often estimated using the FAO-56 method with meteorological data gathered over a reference surface, usually short grass. However, the density of suitable ET0 stations is often low relative to the microclimatic variability of many arid and semi-arid regions, leading to a potentially inaccurate ET0 for irrigation scheduling. In this study, we investigated multiple ET0 products from six meteorological stations, a satellite ET0 product, and integration (merger) of two stations’ data in Southern California, USA. We evaluated ET0 against lysimetric ET observations from two lysimeter systems (weighing and volumetric) and two crops (wine grapes and Jerusalem artichoke) by calculating crop ET ( ETc) using crop coefficients for the lysimetric crops with the different ET0. ETc calculated with ET0 products that incorporated field-specific wind speed had closer agreement with lysimetric ET, with RMSE reduced by 36 and 45% for grape and Jerusalem artichoke, respectively, with on-field anemometer data compared to wind data from the nearest station. The results indicate the potential importance of on-site meteorological sensors for ET0 parameterization; particularly where microclimates are highly variable and/or irrigation water is expensive or scarce

Drying of cereal grains in the Philippines

In IDL-527

Séchage des grains de céréales aux Philippines

Dans IDL-683