Tag: soil moisture

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The use of cover crops and manure to retain soil moisture in Aridisols in Southern Idaho

Purpose

It is important to measure soil moisture in semi-arid regions because future models predict severe droughts and a decrease in rainfall events by up to 40%. The effects of management practices, such as reduced tillage, cover cropping, and manure application, have not been evaluated in the semi-arid and irrigated crop production area of Southern Idaho. In this study, we investigated the effects of cover crops, dairy manure, and tillage on soil physical characteristics (soil water storage, infiltration, runoff, saturated hydraulic conductivity, bulk density) and silage corn yield in silty loam soils. The objectives of this research were to: (a) determine if cover crops and dairy manure increased soil water storage, or if the cover crops were depriving the cash crop of water, (b) determine if infiltration, runoff, saturated hydraulic conductivity, and bulk density were influenced by cover crops and dairy manure, (c) determine if silage corn yield is affected by cover crops and dairy manure, and (d) determine if there are differences between tillage types.

What Did We Do?

This study was conducted at the USDA-ARS Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho. The experimental design was a split plot with four replicates and repeated measures, and the two main experiment treatments were tillage (strip till vs disk/chisel plow). The four sub-treatments were: (a) control (no cover crop or dairy manure), (b) cover crop only (CC only), (c) manure only (M only), and (d) cover crop with manure (CC + M). Treatments that did not receive manure received inorganic fertilizer to meet recommended crop needs based on spring soil tests. Inorganic fertilizer was only applied to manure treatments if spring soil tests indicated that additional nutrients were required. Stockpiled dairy manure was applied with a manure spreader at a rate of 30 ton per acre (dry weight) in the fall after corn silage harvest and incorporated by disking or left on the surface. Both the corn silage and the triticale were irrigated using handlines, as needed, during the water season, which was generally from mid-April through mid-October. Soil moisture was measured using a neutron probe throughout each growing season. Neutron probe measurements were collected every 6 inches to a maximum depth of 60 inches one to two times per month. Soil water storage (SWS) was calculated from 0 to 12 inches, 0 to 24 inches, and 0 to 60 inches using weighted depth increments. A Cornell Sprinkle Infiltrometer was used to measure infiltration and runoff rates, field saturated infiltrability, and rainfall before runoff in the middle of the growing season in 2020 prior to an irrigation event.

What Have We Learned?

From this research, we found that the use of winter cover crops and fall applied solid dairy manure did not improve soil water storage in the semi-arid and calcareous soils in Southern Idaho. Soil water storage tended to be lower in the CC + M plots (Figure 1). The CC + M plots were able to infiltrate more water prior to runoff than the control plots, suggesting that the CC + M plots are drier (Figure 2). Infiltration, runoff, and saturated hydraulic conductivity did not improve with the treatments and remained similar to the control plots. Although some research has shown improvements in soil moisture, soil physical properties, and dry biomass yield when using reduced tillage practices, there were no differences between reduced tillage and conventional tillage. Silage corn yields tended to be highest in the M only plots and lowest in the CC + M plots, however there were no treatment differences in three of the six years of the study (Figure 3). Using triticale as a winter cover crop would be beneficial to increase total dry biomass yields in dairy systems that would like to increase their forage production, however it is not advised if a producer is only looking to increase silage production.

 

Figure 1. Average soil moisture storage (SWS; inch of water) by treatment from 2016 to 2021 in the top 15, top 30, and top 60 inches. Soil moisture storage was calculated from 0 to 12 inches, 0 to 24 inches, and 0 to 60 inches using weighted depth increments. Bars represent mean plus standard error. Columns within years not connected by the same number are significantly different (p<0.05).

 

Figure 2. Average rainfall before runoff by treatment in 2020. Bars represent mean plus standard error. Columns not connected by the same number are significantly different (p<0.05).

 

Figure 3. Average dry biomass yield for silage corn by treatment from 2016 to 2021. Bars represent mean plus standard error. Columns within years not connected by the same number are significantly different (p<0.05).

Future Plans

This spring, inversion tillage will be performed prior to planting silage corn to incorporate the dairy manure into the topsoil. Dairy manure has not been applied to the field since fall of 2020. Inorganic fertilizer will be applied if needed.

Authors

Presenting author

Kevin Kruger, Research Support Scientist, University of Idaho

Corresponding author

Jenifer L. Yost, Research Soil Scientist, USDA-ARS

Corresponding author email address

jenifer.yost@usda.gov

Additional authors

April B. Leytem, Research Soil Scientist, USDA-ARS; Robert S. Dungan, Research Microbiologist, USDA-ARS; Linda R. Schott, Nutrient and Waste Management Extension Specialist, University of Idaho

Additional Information

This research was presented at the virtual ASA, CSSA, SSSA International Annual Meeting in November of 2020. The link to the recorded presentation is found in the citation below. Although this research is not published in a scientific journal yet, we will be submitting a paper to Agricultural Water Management in early to mid 2022.

Yost, J.L., Leytem, A.B., Dungan, R.S., & Schott, L.R. (2020). The Use of Cover Crops and Manure to Retain Soil Moisture in Aridisols in Southern Idaho [Abstract]. ASA, CSSA and SSSA International Annual Meetings (2020) | Virtual, Phoenix, AZ.

https://scisoc.confex.com/scisoc/2020am/meetingapp.cgi/Paper/126244

Acknowledgements

The authors would like to thank Joy Lynn Barsotti for collecting the neutron probe measurements.

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Swine manure and cedar woodchip applications improve soil ecological indicators and improve moisture retention

Purpose

Manure application has long been used as a soil amendment to supply nutrients for crop growth. However, the effects of manure on many other aspects of soil health have been less fully explored, especially in on-farm research settings. The health of soil biological communities has been shown to be positively correlated with the addition of organic materials and soil moisture. This study looked to confirm these observations in an on-farm setting using two types of organic treatments: swine manure and cedar woodchips and their impact on arthropod abundance and soil biological quality (QBS), measured through arthropod adaptations to deep soil living conditions (ecomorphological index).

What Did We Do?

12 plots were established (10 ft x 10 ft) on a commercial farm with clay loam soils, near Julian, Nebraska on a field planted in the second year of a corn-corn-soybean rotation. Plots were assigned to one of three treatments: swine slurry, swine slurry + woodchips, and control plots with no amendments with 4 replications per treatment. Swine slurry was applied at a rate of 4200 gal/ac. Woody biomass was applied at a rate of 10 ton/ac. Swine slurry was applied on all plots in April and woodchips were applied roughly 4 weeks later at the time when plots were established (Day 0).

At establishment (Day 0) and at 5 other days during the growing season (25, 54, 81, 99 and 128 days after establishment) roughly 1 gal of soil was collected from each plot by randomly sampling using a 2-in diameter sampler to a depth of 8-in. These samples were then transferred to Berlese-Tullgren funnels (Figure 1) for extraction of arthropods, a commonly used technique to assess microarthropods in the soil (Ducarme et al., 2002). A 70% ethanol solution was used to preserve the organisms for later analysis. Additionally, a 50 g subsample of the collected material was used to determine the moisture content of the soil at the time of sampling.

Figure 1. Berlese funnel uses light and heat to drive arthropods out of soil or litter sample. Photo credit University of Tennessee Extension.

The QBS method of classification was employed to assign an eco-morphological index (EMI) score based on soil adaptability level of each arthropod order or family (Parisi et al., 2005). Preserved arthropods from each soil sample were identified and quantified using light microscopy. For some groups, such as Coleoptera, characteristics of edaphic adaptation were used to assign individual EMI scores for each arthropod. Each sample was then assigned a total QBS score, which is the sum of the EMI values for each category of arthropod found in the sample.

What Have We Learned?

We observed that on days when soil moisture content was higher, QBS differed significantly among treatments, while no differences among treatments were evident during periods of low soil moisture content. This indicates that soil moisture is the most important soil factor for soil arthropods collected from the top 8 in of soil because they tend to migrate away from heat and drying to more favorable conditions (cooler and wetter environment).

Table 1. Differences in QBS index by treatment at different soil moisture content ranges.
Moisture % Treatment p-value
< 3.3 CON vs SS 0.16
CON vs SSW 0.24
SS vs SSW 0.99
3.4-4.0 CON vs SS 0.08
CON vs SSW 0.03
SS vs SSW 0.73
4.1-5.0 CON vs SS <0.0001
CON vs SSW <0.0001
SS vs SSW <0.0001
CON=control, SS=swine slurry, SSW=swine slurry and woodchips; (p-values are shown for each comparison between treatments at different moisture content ranges)

Thus, it was only when soil moisture was higher overall that arthropod populations in the soil were high enough to show a difference between treatments. For example, on day 54, a more variable moisture content of the soil was observed, with SSW, SS and CON having moisture contents of 4.16, 3.92, and 3.75%, respectively (Table 2).

Table 2. Mean soil moisture content by treatment and time since treatment application
Treatment Moisture %
Day 0 Day 25 Day 54 Day 81 Day 99 Day 128
CON 4.65 3.43 3.75a 3.95 4.77ab 4.31
SS 4.63 3.42 3.92ab 3.71 4.38a 4.1
SSW 4.68 3.72 4.16b 4.27 5.54b 4.63
Effect p-value
Moisture level 0.47
Moisture*treatment 0.05
CON=control, SS=swine slurry, SSW=swine slurry and woodchips; values within columns having the same superscript are not significantly different (p>0.05).

On this same day, QBS was also significantly greater for SSW (QBS=1350) compared to SS (110) and CON (97). Similarly, on day 99 the mean moisture content for the SSW treatment (5.54%) was greater than for SS (4.38%) and CON (4.77%; p<0.05) (Table 3).

Table 3. QBS index by treatment and sampling day
Treatment Day
0 25 54 81 99 128 Mean QBS
CON 156 115 97a 141 105a 150 127.17a
SS 125 106 110ab 135 135b 140 125ab
SSW 140 105 135b 160 141b 160 137b
QBS values having the same superscript within each sampling day are not significantly different. Absence of subscript represent no significant difference between treatments on that day (p≥0.05). CON=control, SS=swine slurry, SSW=swine slurry and woodchips.

In general, we observed that the application of swine slurry with woodchips has a positive effect on soil quality biological index, likely because it also had a positive effect on soil moisture. The application of red cedar woodchips seemed to provide with a good habitat for soil arthropods, which in the future may increase microbial activity and soil aggregation through decomposition of organic matter and binding.

Future Plans

Further analysis will be conducted to examine the arthropod classifications and their role on nutrient cycling more closely. Future research should also seek to confirm these observations in different climates and seasons of the year to observe the efficiency of the treatments, especially woodchips, to preserve soil characteristics that are favorable to microbes and arthropods.

Author

Mara Zelt, Research Technologist, University of Nebraska-Lincoln

Corresponding author email address

mzelt2@unl.edu

Additional authors

Karla Melgar Velis, Graduate Research Assistant, University of Nebraska-Lincoln

Amy Schmidt, Associate Professor, University of Nebraska-Lincoln

Agustin Olivo, Graduate Research Assistant, Cornell University

Eric Henning, Graduate Research Assistant, Iowa State University

Additional Information

Parisi, V., Menta, C., Gardi, C., Jacomini, C., & Mozzanica, E. (2005). Microarthropod communities as a tool to assess soil quality and biodiversity: a new approach in Italy. Agriculture, Ecosystems & Environment, 105, 323-333.

Acknowledgements

Funding for this study was provided by the Nebraska Environmental Trust and Water for Food Global Institute at the University of Nebraska-Lincoln. Much gratitude is extended to collaborating members of the On-Farm Research Network, Nebraska Natural Resource Districts, Nebraska Extension Agents and Michael Hodges and family for providing the land, manure, and effort for this research project. Much appreciation to lab and field workers members of the Schmidt Lab: Mara Zelt, Juan Carlos Ramos, Nancy Sibo, Andrew Ortiz, Andrew Lutt, Seth Caines and Jacob Stover

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Using Soil Moisture to Predict the Risk of Runoff on Non-Frozen Ground

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Why Study Risk and Runoff Potential?

Identifying time periods when land application of manure is likely to contribute to surface runoff contamination is important for making proper management decisions and reducing the risk of surface water contamination.  Recently, a great deal of attention has been focused on reducing nutrient and sediment losses from the winter period.  However, sediment and nutrient losses during the late spring period can be significant and it is important to understand landscape and weather conditions that lead to elevated runoff risk during this time period. 

What Did We Do?

Surface runoff and weather data were gathered at multiple edge-of-field Discovery Farm monitoring stations in Wisconsin.  Soil moisture data were also collected.  Data were analyzed by each storm event during the non-frozen ground period to determine the impact of antecedent soil moisture on surface runoff generation.

What Have We Learned?

Data from the Wisconsin Discovery Farms Program has identified two key time periods with an elevated risk of surface runoff from agricultural fields: the late winter period (February – March) and the late spring period (May – June).  Eighty-one percent of the average annual surface runoff was observed during these two time periods with the late winter period accounting for 50% and the late spring period accounting for 31%.  Data collected over the past 12 years of the Wisconsin Discovery Farm Program indicate that the vast majority (86%) of non-frozen ground runoff occurs when soil moisture is in excess of 35%.   High antecedent soil moisture can indicate risk for surface runoff in agricultural watersheds and can also influence the quantity of surface runoff generated during rainfall events. Avoiding manure applications during time periods with a high probability of rainfall and when soil moisture is at or near threshold levels decreases the risk of surface water contamination. Agricultural producers can utilize soil moisture measurement to guide the timing and rate of manure application to further reduce environmental risk.

Future Plans

Producer education and outreach

Authors

Tim Radatz, Research Specialist , Discovery Farms MN & WI, radatz@mawrc.org

Anita Thompson, Associate Professor, University of Wisconsin – Madison

Fred Madison, Professor, University of Wisconsin – Madison

Additional Information

Radatz, T. F., Thompson, A. M. and Madison, F. W. (2012), Soil moisture and rainfall intensity thresholds for runoff generation in southwestern Wisconsin agricultural watersheds. Hydrol. Process.. doi: 10.1002/hyp.9460

Acknowledgements

UW Discovery Farms Program and Staff

UW-Platteville Pioneer Farm Program and Staff

 

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