Enhancing Pea Inoculants with Molybdenum on Acid Soil
A Demonstration Trial with Smoky Applied Research Association,
Falher (Final Report for 2008)
Background
The micronutrient molybdenum (Mo) is critical in the formation of nodules for some legumes. This micronutrient is normally available in adequate amounts in fertile agricultural soils. However, it may not be available to the rhizobia if the soil is acid. Some research has been done with soybeans in the southern United States that found a yield response to adding Mo to the inoculants in acid soils. There was also an increase in nodulation.
The Mo added to the inoculants had a low cost per acre. Because it is a micronutrient it was added to the inoculants at very low rates. NPARA was using 0.15, 0.3 and 0.4 ounces per acre. They found impressive increases in nodulation using the .15 oz. rate. The cost per acre was less than two dollars.
A field scale trial was done in the Sexsmith area in 2008 and SARDA agreed to do one using large small plots and two different types of inoculant.
Objectives
To provide evidence that might support the work outlined above using different inoculants. To compare a peat based inoculant from Novozyme with molybdenum included, with Soil Implant granular inoculant with sodium molybdate added at time of seeding. To show in tours and meeting that Alberta Pulse Growers are working on topics that could be of economic importance to growers.
Methodology
In a trial site south of Falher at Hector Goudreau’s farm, the plots were marked out in a randomised complete block design with three treatments and four replications. Each plot was to be 100 feet long X 12 feet wide (the width of the Conservapak seeder). That is the way it was seeded with Cutlass peas on May 30th. Seeding had been delayed because of rain. The targeted plant population was 99 plants per square metre (10 per sq. ft.). The three treatments were:
(1) With granular inoculant
(2) With granular inoculant and molybdenum (Mo) added just before seeding
(3) With peat inoculant that included Mo.
The peas emerged well on all treatments after seeding. The Conservapak seeder did leave a rough field finish but the plant stand was good.
Two weeks after seeding the farmer who had RR canola next to the trial sprayed 0.5 l. of glyphosate that took out 60 feet of each of the 100-foot plots. The plots therefore became 40 feet in length. This has affected the reliability of the results because the plot area is smaller. Moisture conditions were good until the end of June, but July brought hot sunny days and drying winds and the crop was not able to meet early promise.
The trial was straight combined by a Wintersteiger plot combine on August 25th, only 87 days after seeding.
Yield results
These were statistically analysed by Dr Kabal Gill of SARDA and are as follows:
Peas with granular inoculant 25.37 bu/ac
Peas w’ granular + molybdenum (Mo) 31.09 bu/ac
Peas w’ peat based inoc. + Mo 31.41 bu/ac
Adding Mo gave a statistically significant yield increase of 22.5% and 23.8% with the peat inoculant from Novozyme being slightly higher. There was not a significant difference between yields from the two inoculants with molybdenum.
The treatment of granular inoculant with sodium molybdate cost about $2.00 per acre for material. The peat inoculant with Mo was provided by Novozyme (Garry Hnatawich) and is experimental.
The site was on an organised SARDA tour on July 31st when 35 people saw the trial. There is interest in the topic being addressed but farmers are waiting for more definite results.
Enhancing Pea Inoculants with Molybdenum on Acid Soil
A Demonstration near Sexsmith 2007 (Final Report for 2008)
Background
The micronutrient molybdenum (Mo) is critical in the formation of nodules for some legumes. This micronutrient is normally available in adequate amounts in fertile agricultural soils. However, it may not be available to the rhizobia if the soil is acid. Some research has been done with soybeans in the southern United States that found a yield response to adding Mo to the inoculants in acid soils. There was also an increase in nodulation.
The North Peace Applied Research Association (Manning, Alberta) (NPARA) has done small plot trials in recent years on acid (ph 6.3) soils at their research farm. Mo was undetectable (< 1 ppm.) according to Norwest Labs. For reasons beyond their control they have not got good yield data. The increase in nodulation on peas inoculated with rhizobia and Mo was impressive, compared with peas inoculated with rhizobia alone.
The Mo added to the inoculants had a low cost per acre. Because it is a micronutrient it was added to the inoculants at very low rates. NPARA was using 0.15, 0.3 and 0.4 ounces per acre. They found impressive increases in nodulation using the .15 oz. rate. The cost per acre was less than two dollars.
Objectives
To provide some in-field evidence that might justify further examination of the value of the work outlined above. To show farmers in the field the work being done.
Bob McCreight has a 3000-acre farm northwest of Sexsmith and he agreed to do a trial on a quarter section near his yard which has a pH 5.9 – 6.0.
Methodology
Bob McCreight suggested the field selected for the trial, because he has several years of soil tests that show the pH to be 5.9 to 6.0. The location of the field is handy being next to Bob’s house and yard.
The peas used were Carneval yellow peas supplied by Bob. The innoculant used for both treatments was Soil Implant granular. The sodium molybdate was in liquid form and was mixed very evenly with the inoculant in an electric cement mixer at a rate that would give 0.3 ounces per acre (8.5 grams) when the inoculant was applied at 8 lbs per acre. The cost of the Mo as sodium molybdate works out to approximately $2.00 per acre. This was done immediately before seeding. The seeding conditions were good with adequate soil moisture.
The crop of Carneval peas was seeded with a Morris Contour airdrill on May 15th. Using GPS guidance alternate swaths of 48’ were seeded with the Mo treatment, and the swaths without Mo were seeded immediately afterwards. The trial thus had four replications times one half mile long. The innoculant used for both treatments was Soil Implant granular.
The growing season was very stressful with very little rain in June and July and the peas remained short (12-14 inches high). The first significant rain came at harvest time, in late August. The idea to have farmers visit the site was abandoned because of the severe drought in the area. (Three other extension tours were cancelled in the west Peace.) Roots were dug up at flowering and nodulation was fairly good. The soil was like concrete because of the drought and differences between treatments were not evident.
Yield Results
Harvested Aug 26th ’08. Strips of ½ mile X 25ft header
Moisture content of peas 14%. Yields averaged from each strip by Lexion 560 combine
| Strip # |
With Mo (bu/ac) |
Without Mo (bu/ac) |
| 1 |
23.79 |
|
| 2 |
|
26.63 |
| 3 |
28.19 |
|
| 4 |
|
29.82 |
| 5 |
27.58 |
|
| 6 |
|
30.60 |
| 7 |
27.10 |
|
| 8 |
|
29.04 |
| Average |
26.67 |
29.02 |
There was significant difference between treatments (p=5% and 1%) with the Mo treatment yielding less than the treatment with no Mo.
This result is puzzling and does not agree with the single strip trial that was done in the area last year, or with the trial done by the Smoky Applied Research Association in 2008.
Funding provided by the
Alberta Pulse Growers
