Location: Sugarcane Research
2021 Annual Report
Objectives
1. Measure and model water-driven processes in agricultural production systems to predict and enable production under constrained conditions that affect ecosystem services.
1.A. Measure sugarcane growth, yield (tons and sugar), and residue in conventional (1.8 m) and wide row (2.4 m) production systems under ambient water conditions.
1.B. Identify field properties and utilization of resources that vary between row spacing including soil carbon and soil moisture content.
2. Measure and model fluxes of water and carbon in these systems and how they are affected by management practices.
Approach
Use field experiments to study the effects of water availability on sugarcane establishment, growth, and yield, and how row spacing-induced changes to water availability and crop physiology affects carbon cycling within the soil, plant, and atmosphere continuum. Laboratory experiments will evaluate how post-harvest crop residue, the largest soil carbon input in these field systems, cycling is impacted by the effects of water, temperature, mineral nutrients, and particle size.
Progress Report
Milestones were met on both objectives and their subobjectives - all of which fall under National Program 211, Problem Area 4, Watershed Management to Improve Ecosystem Services in Agricultural Landscapes, Sub-heading C, measure and predict water-driven agroecosystem productivity and other ecosystem services.
Objective 1.A., ARS researchers at Houma, Louisiana, quantified sugarcane yield and crop residue returns in conventional, single-planted, and a wide-row, double-planted production system under naturally occurring rainfall conditions (e.g., no irrigation) for the second year’s field trials. The wider rows are more intensive, with 50% more linear cane per row. In each experiment, ARS researchers at Houma, Louisiana, monitored soil moisture changes continually using probes inserted into the soil at different depths (Milestone 1).
Objective 1.B., ARS researchers at Houma, Louisiana, measured soil respiration throughout much of the growing season (March to October) using a long-term chamber developed by Li-Cor biosciences (Milestone 2).
Objective 2, ARS researchers at Houma, Louisiana, continued to collect data from two eddy covariance towers to quantify carbon and water flux in the conventional sugarcane production system as well as an adjacent farm with wide-row, more intensive sugarcane production system. (Milestone 3). A third eddy covariance flux tower was erected at the LSU AgCenter Sugar Research Station in St. Gabriel, Louisiana, and began collecting flux and weather data. Flux and biometerology data are currently being analyzed by collaborators at the University of Oklahoma, the University of Arkansas, and the USDA-ARS Grassland Soil and Water Research Laboratory in Temple, Texas.
ARS researchers at Houma, Louisiana, continue work with the Long-Term Agroecosystem Network (LTAR) Lower Mississippi River Basin site by assisting with planning the 2021 LTAR virtual meeting. Data from Objective 1.A. and 2 are being used to meet requirements for the Common Experiment, with both business as usual (conventional tillage and fallowing) and aspirational (reduced tillage, cover crops, chemical fallowing) production practices being investigated. Scientists are also working with Partnerships for Data Innovation (PDI) to contribute to the ARS Meteorological website.
Accomplishments
1. New eddy covariance flux network studies sugarcane contributions to soil carbon sequestration rates. ARS scientists at Houma, Louisiana, suggest Sugarcane (Saccharum spp.) is the world’s largest biomass crop producing over thirty tons per acre each year in Louisiana, including a large amount of carbon dioxide (CO2), an important carbon-containing greenhouse gas. Most of this biomass is removed from the field and processed into sucrose. However, the amount of biomass remaining in the field (composed of roots, ratoons, and extraneous leaf material) is considerable, and comprises the largest organic carbon input into mineral soils used to produce the crop. ARS scientists at Houma, Louisiana, installed three eddy covariance flux towers in sugarcane fields to measure the net CO2 exchange between the atmosphere and the soil. Data from 2020 indicate that Louisiana’s sugarcane production removes about 14 tons of CO2 per acre per year. Of this, 8 tons of CO2 are transferred to sugar mills when the crop is harvested, and 2 tons of CO2 are lost if the extraneous leaf material is burned. Thus, data indicate that between 4-6 tons of CO2 are sequestered each year in soil and belowground plant organs. The eddy covariance flux network continually measures CO2 flux rates to evaluate yearly and geographical variation in carbon sequestration. Depending on the United States carbon market, this work will contribute to establishing a new revenue source to landowners/growers by mitigating CO2 emissions from other industrial sectors.
2. Wide row-spacing has minimal impact on sugarcane yield. ARS scientists at Houma, Louisiana, suggest Sugarcane (Saccharum spp.) is produced in 22 parishes in Louisiana and is the most valuable row crop in the state. Louisiana accounts for half of the United States sugarcane produced each year. The majority of the sugarcane is produced on rows spaced about 6-feet apart from each other. Most sugarcane field equipment, such as tractors and harvesters, are set at this standard row spacing as well. Recently, growers became interested in a wider, 8-foot spaced row, because it may make harvesting more efficient. However, no replicated yield data are available. ARS scientists at Houma, Louisiana, evaluated yields of two commercial sugarcane cultivars over three crop years in both standard and widely-spaced rows. In the plant-cane crop, the wide rows increased sugarcane yields by 7%, when compared to standard-spaced rows. However, over the entire crop cycle there was no significant difference in cane or sucrose yields between row spacing. Thus, whichever row spacing exhibits the lowest operating costs should be the most profitable to the respective sugarcane farming operation.
3. Sugarcane billet planting chemicals dissipate slowly in soil. ARS scientists at Houma, Louisiana, suggest Sugarcane seed pieces, or billets, can be treated with chemicals before they are planted to improve their growth. Previous ARS research at Houma, Louisiana, demonstrates that treating billet seed pieces increases the yield of the subsequent sugarcane crop. However, the fate of the applied chemicals once the billets are planted in soil is unknown. ARS scientists in Houma, Louisiana, and collaborators at Nicholls State University evaluated the dissipation of these chemicals in soil used to grow sugarcane. Soil was treated with fungicide or insecticide and the levels of each chemical was monitored for over 100 days. The data were analyzed and used by ARS scientists at Houma, Louisiana, to compute the half-life of each separate chemical in soil, which varied between 39 and 275 days. Overall, these chemicals decomposed on a medium- to long-time frame and should provide protection for the billet seed pieces against soil-born pests. However, the longer times may indicate that some potential for environmental contamination is possible if chemicals are not used properly. This is the first report for several of these pesticides related to the aerobic dissipation in soils used to grow sugarcane.
4. Increased production through more effective use of water. ARS scientists at Houma, Louisiana, believe Water use efficiency (WUE) refers to the level of crop production, or yield, relative to how much water was used. WUE can be improved by reducing water use while maintaining agricultural productivity. However, in south Louisiana, sugarcane production occurs in a water-abundant region where water availability is rarely limited. Thus, increasing the effective use of water (EUW), which considers crop yield relative to plant-accessible water availability, may provide a better target suited to the region’s hydrology than increasing WUE. ARS scientists in Houma, Louisiana, found that water available for sugarcane transpiration exceeds its water use; therefore, EUW can be increased, or in other words, increasing production can occur through increased photosynthetic water loss (transpiration) to more effectively use available water. Plant traits such as rooting depth can increase plant available water and lead to an increase in crop growth and yield. The information will aid sugarcane breeders in selecting for potential cultivars better adapted to effectively use available water resources.
Review Publications
White Jr, P.M., Wayment, D.G., Mayon, N. 2020. Concentrations of the fungicide azoxystrobin and the insecticide thiamethoxam on sugarcane seed billets following chemical treatment. Journal of the American Society of Sugar Cane Technologists. 40:36-45.
Wayment, D.G., Ledet, H.J., Torres, K., White Jr, P.M. 2021. Soil dissipation of sugarcane billet seed treatment fungicides and insecticide using QuEChERS and HPLC. Journal of Environmental Science and Health. 56(2):188-196.
Wei, Z., Wang, J.J., Fultz, L.M., White Jr, P.M., Jeong, C. 2021. Application of biochar in estrogen hormone-contaminated and manure-affected soils: Impact on soil respiration, microbial community and enzyme activity. Chemosphere. 270. Article 128625. https://doi.org/10.1016/j.chemosphere.2020.128625.
Xin, F., Xiao, X., Cabral, O., White Jr, P.M., Guo, H., Ma, J., Li, B., Zhao, B. 2020. Phenology and gross primary production of sugarcane plantations in Brazil and USA. Remote Sensing. 12(14):2186. https://doi.org/10.3390/rs12142186
