Using crops to improve Sodic Soil and increase productivity

Using deep rooting plants (lucerne, tillage radish and canola) to improve sodic soil and increase productivity.

Year of study: 2014 to 2018

Location: Rosedale / Glengarry Gippsland Victoria

Farm size: 480 Ha

Farm type: Sheep 3,000 Merino cross / Cropping

Soil type: Sodosol

Average annual rainfall: 600 – 650mm

Topography: East to North East facing terraces

Sodosols are a common soil type on the Eastern Victorian plains.
Although Gippsland Sodosols are reasonably productive, these soils are naturally low in organic matter, leached of nutrients, and have a layer of sodium rich clay at around 20 cm depth. The sodic layer becomes boggy in wet conditions, hard in dry conditions and is generally unhospitable to root development. These factors create a series of natural constraints to production.

Sodic Soils - Scott Langley

Project details

soil-case-farm1-soilprofile

Objectives:

  • Use deep rooting plants (lucerne, tillage radish and canola) to penetrate the sodic layer, access deep nutrients, open soil structure, enhance biological function and leach sodium down the profile.
  • Maintain lucerne as an under crop to minimise in-crop nitrogen requirements.
  • Provide maximum ground cover in a mixed farming system and fill feed gaps.
  • MAKE MONEY!

Basis: Several experiments over the last two decades have shown that most sodic soils can be ameliorated by a low capital input investment  ie:  Phytoremediation:  (Robbins 1996, Ahmad 1990, Ilyas 1993, Qadir 2001). This amelioration works through plant root action that helps dissolve native calcium carbonate to supply adequate levels of calcium without the application of an amendment.

Scientific research has also shown that Brassica crops stimulate soil mineral N accumulation: (Ryan, Kirkegaard, and Angus.)

More Information on Sodic Soils can be found at http://vro.depi.vic.gov.au/dpi/vro/vrosite.nsf/pages/sodic_soils

Farm details

soil-case-farm1-map2

Scott Langley started his career in agriculture in 2003, running sheep on leased land after studying at Dookie. He purchased the home block and has added two parcels of land in the last 4 years. Now married with a young family, he is close to a 50/50 sheep cropping mix.

In Scott’s words he “doesn’t want to die wondering”. A big believer in grazing crops, he says “Get what you can with grazing, hopefully then the grain is profit.” He loves the wool industry, but wishes there was more money in the finer end of the market.

Scott is interested in what’s happening under his feet, always looking at new alternatives, to try or push old methods and to further boundaries. Lime is used as a primary and ongoing component of the operation to address pH and sodium, stock grazing is managed to provide maximum residual groundcover and paddocks are rested sometimes to allow a build-up of decaying plant residue at the soil surface before re-grazing.

Scott has noticed massive increases in worm activity after canola and sees the use of deep rooted crops as an important part of improving soil structure for ongoing productivity gains.

Paddock details

Map of Langley farm showing paddocks

Rainfall East Sale 2014-2017

Rainfall in East Sale from 2014 to 2017

Summary of results

Despite difficult seasonal conditions, (especially 2017), the lucerne in paddock 2 showed:

  • strong productivity performance when compared to typical pasture species
  • increased number of lambs at marking and maintained ewes in condition
  • root penetration through the sodic layer. No deep roots were evident at depth in pasture Paddock 1
  • exchangable Sodium% (ESP) reducing in the profile depths tested and an increase in nutrient levels

 

Scott also added:

  • the soil structure, rainfall penetration and response to rainfall is definitely better in the Lucerne paddock
  • with time, I hope to reduce nitrogen fertiliser use due to increased soil nitrogen levels
  • I didn’t harvest a crop in the lucerne paddock but this remains an aim. Crop grazing still provided good return on investment.

Paddock summary

Summary table for all paddocks for 3 year period
Two soil core samples and a sample of the lucerne roots

Soil cores from paddock 1 (left), had no root development beyond 10cm. Soil cores from paddock 2 (right) consistently had lucerne root development up to 80-90cm.

Paddock 1: 14.2ha

Paddock 1 table for 3 year period

Barley grass can provide good feed early in the season but by mid spring onwards provides very little dry matter. In summer the seeds cause issues for the sheep’s eyes.

Lucerne was planted into the paddock in year 2 but failed to establish well.

The paddock was used as a sacrifice paddock at the end of the last 3 summers. This gave the other feed paddocks a decent spell and a chance to produce more productive feed. Although it has not produced much, it bridged a gap for feeding sheep on the property.

There were no sheep condition scoring completed after grazing this paddock.

Soil tests have shown a slight increase in Exchangeable Sodium Percentage in the 0-10cm, but a decrease at the 10-30cm depth. There has been an insignificant change in the other macro and micro nutrients.

Paddock one, is a pasture paddock dominated by barley grass with some cocksfoot, other grasses and flat weeds.

Paddock 2: 17ha

Paddock 2 table for 3 year period

October to December 2014

  • Sown to “Stamina GT6″ Lucerne, 15kg/ha with a Duncan drill, 6” row spacing with 200kg/ha of DAP, (36kg of N)
  • ‘Stamina GT6″ is a summer active which maintains good fodder for many years and can withstand most diseases and pests
  • The plan – to intercrop this paddock every second year. No crop sown into Lucerne, year 1
  • Establishment counts showed an average 200 lucerne/sq.m, 32 grasses (mainly ryegrass)/sq.m and 12 broadleaf weeds/sq.m
  • Lucerne lightly grazed for a month to ensure longevity of pasture and encourage plant development
  • Produced 1.8 t/ha of dry matter with 1.1 t/ha of dry matter residual
  • Ewe’s went in at condition score 2.4 and out at 2.6
Lucerne at first grazing, December 2014

Summer/Autumn 2015

  • Lucerne fertilised with a 1-1 super/potash blend at 200kg/ha
  • Grazed for the second time at the beginning of February – only produced a further 0.1t/ha
  • 400 lambs averaged weight of 45kg. After two weeks they gained 4.9kg on average (352g/day)
  • After a month another 535 lambs were added to eat down the lucerne in preparation for sowing
  • All lambs removed at the beginning of April – only 0.2kg/ha of dry matter remaining
  • Growing conditions still good, lucerne continued to grow, producing 0.88t/ha of dry matter
  • 500 ewes grazing the lucerne for 24 days. Ewe’s were one week off beginning to lamb and then had a lamb at foot when removed, no condition scoring was done. There was only 70kg/ha of dry matter remaining.

For the season the lucerne produced just over 3t/ha of dry matter and satisfied a number of points that Scott wanted to achieve. These were filling the feed gap and providing maximum groundcover. The stock that grazed the lucerne had excellent health at all times. At the first grazing, the ewe’s were joined on the lucerne and they scanned at 150%. For the season approximately 60kg/ha of nitrogen was removed.

Winter 2015 to Autumn 2016

  • 15 June, Scout wheat sown into the lucerne with 100 kg DAP
  • Early spring shortage of feed so wheat/lucerne/ryegrass was grazed – produced 2.5t/ha of dry matter. Part of the paddock was fenced off to take the wheat through to harvest
  • At next grazing in November, it was felt that the wheat would not produce a crop that could be harvested and the whole paddock was grazed. This produced 2.7t/ha of dry matter
  • Ewes went in at condition score 2.1 and left three weeks later after joining at condition score 2.6
  • January 200kg/ha of Super/MOP blend
  • June 35kg/ha of Copper, Zinc, Manganese and Boron
  • Due to dry weather conditions this paddock was needed often and was grazed in January, March and April. The last grazing was used for the lambing ewes.

The lucerne continued to provide a valuable source of feed when required for stock. The high scanning rate of 146% and 112% at marking is attributed to the excellent feed. For the season it produced just over 6.4t/ha of dry matter and satisfied a number of points that Scott wanted to achieve. These were filling the feed gap and providing maximum groundcover. The stock that grazed the lucerne had excellent health at all times.

Paddock 2 comparing three years

Paddock 3: 9ha

Paddock 3 table for 3 year period

Year 1

Sown to Canola at a rate of 3kg/ha using a Rubin Speed Disc.

Harvested in December yielding 1.98t/ha with an oil percentage of 42.1%. This removed 79kg/ha of nitrogen. No grazing took place on this paddock in Year 1.

Year 2

Scout wheat was harvested in December, yielding 3.4t/ha with a protein percentage of 12.2% indicating that the fertiliser applications matched the yield potential. This removed 85kg/ha of nitrogen.

The paddock was grazed once having experienced drier conditions during its growing period. At this grazing it produced 3.6t/ha of dry matter, with the sheep grazing the paddock for one week. Due to the stage of the season and the need for feed, the tillage radish was continued and a cereal did not follow.

Year 3

Paddock three was not cropped but the tillage radish remained until it started to go to seed in spring.  The paddock was then sown to lucerne in September 2017. Once established, the paddock was grazed four times.  As the stand was very young, the conditions were dry and the tillage radish dried out the soil profile, yields were low with approximately 0.7t/ha produced.

Combing the yields of the tillage radish and lucerne, the paddock produced just under 2 t/ha of high quality feed during a tough year. Due to the lucerne being sown, the costs for the paddock increased and led to a small loss being made.

Paddock 3 in 2014 and again in 2015
Radish and Soil Cores

Methodology

Soil test

(CSBP – NATA accredited)
100m transect diagonal across each paddock. 30 samples on each transect taken with Christie Hydraulic sampler. Samples split into 0-10 and 10 – 30cm and bulked to form 2 samples per paddock. No formal analysis of soil change to be measured. Soil tests to inform discussion.

Production Measures

Total yield against inputs on the three test paddocks.
$ profit per hectare
Lucerne persistence under a cropping regime.

Methods
Grazing Dry Matter Yield

  • Pre and post grazing cuts at every grazing event on the three test paddocks
  • Five random quadrats cut to grazing height, weighed, oven dried and then reweighed
  • Presented as tonnes p/ha
  • Converted to $ p/ha.

* the rate at which the DMY is converted to $ is dependent on feed quality. This has been decided by consensus with Scott, SFS rep Janice Dowe and and independent agronomist.

The grazing paddock was rated at $100/t whereas the lucerne was rated at $250/t.

Lucerne Plant Count

  • Plant count in 5 quadrats at establishment stage and then once per year prior to grazing
  • Presented as plants per ha.

Sheep weight gain and condition score

  • Pre and post grazing at every grazing event
  • 20% of flock randomly selected, weighed and condition scored
  • Presented as weight and condition gain or loss per paddock.

Wheat, Canola and Barley Crop Yield

  • Every harvest on both cropping paddocks
  • Subsamples sent for protein/oil analysis
  • $ yield per ha.

Inputs

  • Seed
  • Nitrogen
  • Other Fertiliser
  • Chemical
  • Presented as $ p/ha and kg p/ha per paddock.

Profit of each paddock

  • $ per ha.

Acknowledgements

Many thanks to Scott Langley for his assistance and allowing monitoring and evaluation of the paddocks. Thanks also to Janice Dowe (Southern Farming Systems) for her persistence and effort in gathering and evaluating the data.

The Healthy Soils Sustainable Farms project is supported by the West Gippsland Catchment Management Authority through funding from the Australian Government’s National Landcare Programme.

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3 thoughts on “Using crops to improve Sodic Soil and increase productivity

  1. I am very disappointed that a challenging site like this was not considered for the use of Humusplus4. I have suggested it for trials, but some how, the organisers cannot look at anything different to the same old, same old. We will never move forward if we do not put a toe in the water.
    Regards,
    Jeff

    1. Hi Jeff, Scott uses crops to improve soil condition as well as lime, gypsum, and conventional high analysis fertiliser. It is not up to us to tell him what inputs to use. The purpose of this site was to show that using deep rooted plants can improve soil conditions and productivity. There are many other things that can be used in combination including the use of your product and the one listed in the comment below yours.

  2. Better results if you use a skip row system when planting the lucerne. You can then plant between the rows with a cereal, get better weed control and end up with a harvest.
    Stop using synthetic based P fertiliser such as SSP and look more closely at the RPR based fertilisers such as BioAg BioAgPhos for better P release and less acidity issues