Progress Report on Soil pH and Nutrient Improvement with Forage Brassicas and Buckwheat

Trial Site: Fairview Research Farm

Research Coordinator: Dr. Akim Omokanye

From: Peace Country Beef & Forage Association 2017 Annual Report


Soil acidity is identified by the measurement of soil reaction (pH). The reaction is alkaline when the pH value is above 7.0; neutral at 7.0; and acidic below 7.0. In practical terms, soils between pH 6.5 and 7.5 are considered neutral. Soils in the range of 5.6 to 6.0 are moderately acidic and below 5.5 are strongly acidic. The distribution of acidic soils in Alberta according to Alberta Agriculture & Forestry (http://www1.agric.gov.ab.ca/ $department/deptdocs.nsf/all/agdex3684/$file/534-1.pdf?OpenElement), indicates that acidic soils occur most frequently in central Alberta and in the Peace River region. Recent data from PCBFA’s on-farm studies seems to show the potential for pH in the sub-surface soil (6-24”) to be slightly higher than in the surface soil. If this holds true, then we may be able to use some cover crops with deep rooting systems, and those with potential to scavenge nutrients (such as purple top turnip, tillage radish, daikon radish & barkant turnip) as options to improve surface soil pH, instead of liming.


Objectives

  1. To examine the potential of a variety of annual cover crops for improving surface soil nutrients and pH

  2. To determine forage dry matter and quality for beef cattle production

Methods

  • Project Site: Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview.

  • Previous Crop: Oats for greenfeed in 2016 and 2015

  • Site soil information (0-6” depth): Soil tests done at Exova laboratory (Edmonton) prior to seeding showed pH = 5.6 and soil organic matter = 7.8%.

  • The field was cultivated (disced and harrowed) before seeding.

  • Experimental Design: Randomized complete block design in 4 replications.

Treatments: 4 forage-type brassica crops and buckwheat were tested:

  1. Purple top turnip (brassica) @ 3 lbs

  2. Tillage radish (brassica) @ 6 lbs

  3. Daikon radish (brassica) @ 13 lbs

  4. Barkant turnip (brassica) @ 3 lbs

  5. Buckwheat @ 50 lbs

Seeding Date & Rate: Seeding was done on June 1


Seeding method: 6-row Fabro plot drill with 9” row spacing


Fertility: No fertility was applied.


Spraying: In-crop spraying was done once with Lontreal 360 (except for buckwheat)


Forage yield & quality, and crop root nutrients were determined.


Results and Interpretation

Forage Dry Matter (DM) Yield

For the purpose of livestock production, the above ground forage DM yield of the crops tested was highest for tillage radish (7353 lbs DM/acre), followed closely by daikon radish (7128 lbs DM/acre) and then buckwheat (6037 lbs DM/acre). Generally, the 2 turnips had lower forage DM yield than radishes and buckwheat.


Forage Quality

Generally, both purple top turnips and barkant turnips had higher forage crude protein (CP), total digestible nutrients (TDN), net energy for lactation (NEL), gain (NEG) & maintenance (NEM), Ca, K, Fe and RFV than other crops tested.


The requirements of CP, TDN, Ca, K, Mg, S and Zn by mature beef cattle were all met by all brassicas and buckwheat tested.


All crops had enough forage P for a dry gestating beef cow, but only buckwheat and daikon radish seemed to have sufficient forage P for a lactating beef cow.


Except for buckwheat, all crops tested had enough forage Na for young and mature beef cattle.


None of the crops had adequate forage Cu for young and mature beef cattle, which is 10ppm Cu.


Root Quality

The root CP was highest for purple top turnips (14.5% CP), followed by barkant turnips (12.8% CP).


Both purple top turnips and barkant turnips generally had higher root TDN, NEL , NEG, NEM and P than other crops.


Buckwheat generally had far less root CP, TDN, NEL , NEG, NEM, P, K, Na and S than other crops.


Future Plan

Soil tests will be done in spring 2018 to determine nutrient credits and soil pH changes from the treatments in 2017.


The same set of crops will be seeded again in the same plots in 2018.


Cost-benefit and soil health analysis will be carried out on emanating field data.

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