Mitigating and preventing flood-related soil quality degradation using cover crop blends
Flooding causes a wide range of soil degradation issues including compaction, soil fertility loss, and reduction of mycorrhizae. These detrimental alterations can limit farm viability by reducing yields. This research aims to assess the ability of six different cover crop treatments in alleviating damage done to soil by flooding. Forage radish, winter rye, hairy vetch, lupine, and a mix of all four were chosen for their potential benefits of remediating flood-damaged soils and a fallow treatment was used as a control.
Three farmers from Arethusa Farm, Adam’s Berry Farm, and the Intervale Center identified three flood-prone areas currently cultivated. In the autumn of 2012, four replicates of six different cover crop treatments were planted at each of the three identified sites. In the late spring the cover crops were disced in at Arethusa Farm and following agricultural management practices, corn was planted as an indicator crop. One replicate of the six treatments was planted at Adam’s Berry Farm as a demonstration for a field day. The Intervale Center site was abandoned after initial spring 2013 soil sampling due to a prolonged saturation event.
Soil health was or will be measured for compaction by penetrometer readings, soil fertility with KCl extraction for nitrogen and ammonium acetate for other relevant soil fertility elements, and mycorrhizae colonization by ink staining. Data has been presented at a field day in NOFA’s fall workshop series. A field-season, weekly WordPress blog1 recorded field updates, analysis of results, and agricultural current events. A presentation in January 2014 will also be given at Cornell’s Cooperative Extension’s Climate Change Session of the 2014 Empire State Producers Expo in Syracuse, NY. In addition, a table with information from this research will be available during the NOFA winter conference in February. 1www.floodedsoils.wordpress.org
Work under Objective I
In order to record saturation, a log of flooding depth was not recorded as originally proposed. Instead, Winooski crests recorded on NOAA website were used as a proxy. At Adam’s Berry Farm, a Watermark sensor was installed with eight sensors six inches underground, one recording temperature and the other seven recording soil moisture tension in centibars every two hours.
Baseline soil data was collected in the autumn of 2012 at all three sites with a 1-inch diameter, 12-inch long Oakfield soil sampler. In the spring and autumn of 2013, five soil samples per plot were taken for data collection on cover crop treatments. The five soil samples were composited for each plot. In order to maximize funds, soil samples were analyzed by Lindsey Ruhl using UVM’s AETL equipment. Soil samples were analyzed for nitrogen using KCl extract and other soil nutrients using ammonium acetate. Analysis of pH will be done in 2014 and calculations for percent base saturation and cation exchange capacity will also be done in 2014.
In the spring and autumn of 2013, compaction was measured at five random locations in each plot using a cone penetrometer every four inches up to a depth of twelve inches. Bulk density measurements were taken with two 5 cm X 5 cm cores once randomly at each plot with an AMS hammer core. Due to equipment availability, a depth of four inches was achieved, not twelve.
Mini-infiltrometers measured infiltration rates after the cover crop planting. Due to lack of discernable difference in readings between plots and time requirement, this test was not repeated. Samples have been dried for analysis with the Cornell Sprinkle Infiltrometer. The tests have not been conducted due to temperamental tendency of instrument calibration and will be attempted again in 2014. In lab, the Cornell Sprinkle Infiltrometer also allows for calculations of stable aggregates and will be used instead of the water bath method.
Work under Objective II
Sweet corn was planted at Arethusa Farm in June 2013. It was planted as an indicator crop to show nutrient deficiencies and effect of treatment on yield. Plants were visually assessed. Heights were measured before and after tasseling. The third leaf from the top was cut on the base from five random plants from each plot. They were dried and ground and will be analyzed for nutrients in 2014. Ears of corn have been collected and fresh and dry weight recorded. Another test was added to measure sweetness of the corn. What good is the yield if the product is sub-par? Three ears of corn were randomly chosen from each plot and each was measured at three locations on the ear using a Brix measurement device.
Field preparation was delayed due the rains in May and June. As a result, the indicator crop was not planted at Adam’s Berry Farm and the Intervale Center due to concerns of a late field start.
Work under Objective III
Biomass was collected in a one foot quadrant from each plot. The vegetation from each quadrant was separated by cover crop type and other. The weights were recorded for fresh and dry states.
In spring of 2013, 6X6X6 inch root samples were taken from all plots at Arethusa Farm and Adam’s Berry Farm. Roots from three of the four replicates at the Intervale Center were collected before the rains from the two wettest consecutive months ever recorded in VT occurred. The depth of the root samples was curtailed due to space restrictions and shallow root penetration depth. In the fall of 2013, 5 cm X 10 cm cores in a AMS Hammer were used to collect root samples.
Due to the delicacy of the roots and inordinate amount of time to clean them, roots were not cleaned for mass weight. However, in November and December of 2013, a subsample of each sample collected in spring and autumn of 2013 was cleaned and preserved for mycorrhizae staining in 2014.
A weekly blog was kept with updates to field site, data, and agricultural current events. The premise of this research was presented at NOFA’s winter conference intensive workshops in 2013. A field day was held in September in NOFA’s fall workshop series. Fifteen farmers and University of Vermont personal attended. A brochure was created “Cover Crops to Cope with the Effects of Flooding on Soil Fertility” and dispersed at the field day. Another brochure will be created with more information and dispersed when analysis is complete. The field day was conducted on site without any additional media like the video originally proposed. Instead, there was a visual before and after with one site established with cover crops and another with a mature stand of corn.
Sept/Oct 2012: Seeding cover crops. Setting goals for the first factsheet on flooding; Set up web page, Start blog.
Cover crops were seeded later than expected. This is a busy harvest time of year for farmers and my priority was not necessarily their priority. Furthermore, I did not have the knowledge of how long disced crops would need to decompose nor the skill to operate the machinery myself. Information on climate change and flooding effects on soil were collected. The webpage (www.floodedsoils.wordpress.org) was created and maintained on a weekly basis during the growing season. If a week was missed, two entries would be made the next or additional entries past initial end date.
November 2012-March 2013: Visual assessment of cover crops. Write factsheet, Analyze the soil fertility data.
Visual assessment of cover crops was noted and pictures taken. One factsheet has been written and a new one with more complete analysis of results will be created in 2014. Biomass samples of nutrient data and roots of mycorrhizae colonization have yet to be analyzed for statistical results.
January-February 2013: Prepare for NOFA Winter Conference Intensive Workshop
A presentation on “Flooding, Soil Quality, and Cover Crops” was given during NOFA’s Winter Conference.
April/May 2013: Termination and tillage of cover crops, Post flood fertility tests, Post flood soil physical test, Plant corn. Prepare for the NOFA Summer Conference.
Cover crops were terminated later than anticipated. This was due to the time requirements necessary to collect all samples. Cover crops were disced in at Arethusa Farm and Adam’s Berry Farm. Cover crops were not tilled in at the Intervale Center due to prolonged and prohibitive length of soil saturation with water. Post flood fertility and soil physical tests were conducted at Adam’s Berry Farm and Arethusa Farm. Corn was planted at Arethusa Farm and cover crops for demonstration during the field day were planted at Adam’s Berry Farm. Preparation for NOFA Summer Conference did not occur. Instead, preparation was done for the field day and was a part of NOFA’s fall workshop series.
June 2013: June Nitrate Test, Seedling tissue tests. Complete rough draft of fact sheet and brochure.
Soil samples were collected in June. Corn tissue was collected for analysis. Brix measurements were conducted to test for sweetness of corn. Outline of fact sheet and brochure created.
July/Aug 2013: Assessing corn yield and deficiency symptoms in corn crop. Finalize and print fact sheet and brochure. Field Day, NOFA summer conference.
Corn yield has been collected, dried, and weighed. Corn leaf samples have been dried and ground, but not analyzed. These measurement will be finished in 2014. Field day moved to NOFA fall workshop series.
September 2013: Field Day
The field day had 15 participants and the brochure/factsheet was disseminated at this time.
Impacts and Contributions/Outcomes
In addition to the planned presentations, this work will also be shared at Cornell’s Cooperative Extension’s Climate Change Session of the 2014 Empire State Producers Expo in Syracuse, NY in January and during NOFA’s winter conference in February. Furthermore, Adam Hausmann of Adam’s Berry Farm planted forage radish for the first time after attending the field day.
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