Location: Sugarcane Research
2025 Annual Report
Objectives
Objective 1: Determine and evaluate critical water efficiency optimization parameters that impact sugarcane crop production systems in temperate environments.
Sub-objective 1.A: Improve crop coefficients for reference ET models that are reliable along the sugarcane life cycle and across sugarcane growing areas in U.S. with differing climatic zones and water regimes, including deficit and excess-water conditions.
Sub-objective 1.B: Improve ET models for water management at field to regional level by separating transpiration and soil evaporation fluxes using stable isotopes of hydrogen and oxygen in water.
Objective 2: Develop holistic stochastic optimization models and decision support tools to improve the sustainability of sugarcane production systems in temperate environments.
Objective 3: Evaluate and/or develop conservation best management practices that positively influence soil water and carbon cycling in sugarcane production systems in temperate environments.
Sub-objective 3.A: Characterize how long-term (16+ y) sugarcane crop residue management affects soil moisture storage, C sequestration, and crop yield.
Sub-objective 3.B: Characterize how new tillage and fallow cover cropping practices affect soil moisture storage, C sequestration, and crop yield.
Approach
Through greenhouse and field experiments, improve crop coefficients for reference evapotranspiration (ET) models that are reliable along the sugarcane life cycle and across sugarcane growing areas in U.S. with differing climatic zones and water regimes, including deficit and excess-water conditions; and Improve ET models for water management at field to regional level by separating transpiration and soil evaporation fluxes using stable isotopes of hydrogen and oxygen in water. Employ data collected in the field to populate DSSAT input modules to evaluate how changing climatic conditions will affect sustainable sugarcane production. Characterize how long-term (16+ y) sugarcane crop residue management affects soil moisture storage, carbon sequestration, and crop yield. Characterize how new tillage and fallow cover cropping practices affect soil moisture storage, carbon sequestration, and crop yield.
Progress Report
Year 2 has been productive. Using the mobile lab that houses the water isotope analyzer and multiplexer, preliminary measurements of the isotopic composition of evapotranspiration were made. ARS researchers at Houma, Louisiana are continuing these measurements because it is very difficult to obtain useful data for partitioning evapotranspiration into evaporation from soil and transpiration under the typical environmental conditions. Nonetheless, progress was made in the measurements and techniques, and current measurements are better as a result.
This year the minirhizotron project continued in second ratoon. Through a collaboration with a professor and graduate student at the University of Texas at Arlington, a computer method using deep learning and artificial intelligence is being developed to analyze sugarcane roots in the minirhizotron images. Approximately 10,000 images have been annotated in an effort to develop the world’s largest annotated database of sugarcane roots to develop AI tools for root analysis.
Using a stable isotope analysis, a study measuring the depth of water uptake by sugarcane was completed. This study included the minirhizotron site and a “heavy land” and “sandy land” to understand the role of soil texture on water source use. Precipitation in 2024 was above average and provided an excellent contrast with the record drought in the previous year (2023). This study has led to surprising results about water source use by sugarcane and the importance of deep roots and access to deep water/groundwater even in wet years.
Further work was done in finding differences in photosynthesis and transpiration at the leaf and plant level to discover traits associated with sugarcane water use and its relationship with growth and productivity.
Accomplishments
1. Measuring water source use by sugarcane. The purpose of this research is to determine where in the soil profile sugarcane access water in both drought and wet years. A third of all transpired water came from the shallow soil in a wet year and was preferentially taken up when the shallow soil was very wet. This water source, however, was largely unavailable during a drought, accounting for only 9% of water uptake. Deep water/groundwater accounted for 72 % of sugarcane water uptake during a drought year and 42% of sugarcane water uptake during a wet year. ARS researchers at Houma, Louisiana found that even in this rain-abundant agroecosystem, deep water/groundwater is critical in drought years for sugarcane survival and is still necessary in wet years for maximum growth and yields. If adequate access to groundwater is available to maintain sugarcane transpiration, sugarcane production is largely unaffected by drought. When present, the removal of hardened plow pans, which reduce root penetration into deep soil layers, is necessary. This is particularly important in soils with heavy clay (approximately 40 % of sugarcane fields in south Louisiana) where reliance on deep water is greater than in soils with lower clay content. This study also demonstrates the importance of deep rooting by sugarcane varieties and the need to maintain this trait in variety development.
2. Measuring agroecosystem water use efficiency. The purpose of this study was to measure water use efficiency of the sugarcane agroecosystem and determine the dependence of WUE on precipitation. ARS researchers at Houma, Louisiana found that WUE was not dependent on precipitation in that plant-available water within the soil profile always met transpirational demands adequately, apparently even in drought years such as 2023. This means that water availability in this rainfed agroecosystem exceeds the demands of evaporation from the soil and transpiration to a point that transpiration could increase without a negative impact on productivity from water limitation. As varieties with improved photosynthetic traits are produced, their potential increased transpiration will not negatively impact water resources.
3. Heavy application of manure positively affects soil biology.. ARS researchers at Houma, Louisiana believe much of the dairy production in the U.S. is concentrated in small geographical areas. Dairy manure applications to cropland are a common practice as an important source of crop nutrients, but little knowledge was known of the effects of manure on other soil and biological factors, and the effect these factors have on crop production. To evaluate the impact of a one-time heavy application of manure as an alternative to annual application to croplands ARS researchers in Kimberly, Idaho; Lubbock, Texas; Brookings, South Dakota; Fort Collins, Colorado; Akron, Colorado; Adams, Oregon; Columbia, Missouri; Morris, Minnesota; and Houma, Louisiana, monitored soil fertility-associated biological and chemical properties for two years following incorporation of a heavy application of dairy manure to a semiarid soil. Although heavy application of manure resulted in a reduction in corn yields from lower nutrient availability the first year of application, yields rebounded in the second. Additionally, the impact on the soil biological and chemical properties was positive in the long-term indicating the heavy application approach could be a valid alternative to annual applications. Contributions from Houma, LA, indicated the higher levels of nitrogen remained in soil from manure additions, when compared to mineral fertilizer additions, even after two years. Researchers, soil fertility consultants, and dairy producers can use this information to develop better manure management plans, particularly in regions where animal manure is abundantly available
4. Sugarcane-derived biochar improve crop yields. Over 430,000 metric tons of bagasse remain after powering boilers to process sugarcane in year in Louisiana and represents a disposal problem to sugar factories. ARS researchers from New Orleans, Louisiana, and Houma, Louisiana, investigated converting the material to biochar, applying it to soil, and its effects on subsequent sugarcane yields in a 4-year field study. The biochar was applied at two rates: 0.8 and 1.6 Mg ha-1 at planting. Considering the cumulative sugar yield over 4 years, additional income can be realized from amending soil with biochar. The best outcome resulted in estimated sugar profits up to an additional $6837 ha-1 at a raw sugar price of $0.82 kg-1. This represents a potential revenue stream for both sugar factories and sugarcane growers.
Review Publications
Ellsworth, P.Z., White Jr, P.M. 2024. Carbon isotopic composition reflects intrinsic water use efficiency and not its component traits in sugarcane. Tropical Plant Biology. https://doi.org/10.1007/s12042-024-09367-z.
Wayment, D.G., Wright, A.A., Bergeron, D.R., Mccollam, G.A., White Jr, P.M. 2024. Soil dissipation and efficacy on itchgrass of soil-applied residual herbicides pendimethalin and clomazone in Louisiana sugarcane. Pest Management Science. https://doi.org/10.1002/ps.8432.
Dungan, R.S., Acosta Martinez, V., Lehman, R.M., Manter, D.K., Mikha, M.M., Reardon, C.L., Tarkalson, D.D., Veum, K.S., Weyers, S.L., White, Jr., P.M. 2024. Short-term effects of a heavy dairy manure application on soil chemical and biological indicators in an irrigated semiarid cropping system. Agronomy Journal. 117(1). Article e21737. https://doi.org/10.1002/agj2.21737.
Lima, I.M., White Jr, P.M., Webber Iii, C.L. 2025. Four-year field study: Increased yields in soils amended with biochar from sugarcane residues. Biochar Journal. 24. pg 970-991. https://doi.org/10.1007/s12355-025-01600-7.