Mar 24,2017 at 07:08 am By Admin - Rocks Gone
Farm Weekly March 23rd 2017
Plumbing the depths of deep ripping
There’s an exponential increase in the depth of knowledge, the deeper deep ripping goes.
Or so it seems from the wealth of information provided at the Northern Agri Group (NAG) Autumn Update last week.
According to Department of Agriculture and Food (DAFWA) research officer Wayne Parker, the majority of NAG growers are deep ripping to a depth of about 400 millimetres (16 inches) to combat subsoil compaction.
But larger, heavier machinery has pushed these hard pans to depths greater than 400 millimetres.
Mr Parker said trials to investigate deep ripping led to a DAFWA-designed double-row trial ripper which has shallow leading tines and deeper following tines, allowing for a greater depth of penetration with reduced draft and less cloddiness.
Added to the deep ripper are inclusion plates to incorporate the topsoil and/or soil ameliorants to depth behind the tine.
The addition of inclusion plates to deep rippers gives growers the ability to remediate multiple constraints in one pass, improving efficiency and return on investment.
Row spacings were also considered in last year’s trial on Malkana, Piet and Dale Diepeveen’s property, east of Binnu, because grower experience was the extra draft added by ripping deeper with inclusion plates, exceeded the capacity of big tractors.
Mr Parker said the preferred option was to increase the tine spacing rather than reduce the width of the ripper – allowing for increased depth and ripping speed and leading to increased productivity.
The rationale is that yield response is related to the volume of decompacted soil.
Mr Parker said tines with narrower spacing (50cm, 20in) would break up a greater volume of soil than wide tines (1m), but if the response from ripping at double spacings was sufficient, then it was possible the business could earn more by ripping a greater area despite decreased yield response.
Irrespective of tine spacings and soil type, yield improved through ripping below 400mm, with greater yields at 50cm spacings than at a metre.
Interestingly, using winged points tended to provide additional yield when ripping on metre spacings, though the response was not statistically significant.
Mr Parker said the reason for adding wings to points was to increase breakout width and reduce the volume of unfractured soil between tines.
“Increasing the width of the point increases the volume of soil lifted, then dropped, to lengthen fracturing the soil,” he said.
“At metre spacings, the winged point did improve yield response, when compared to the standard point.”
He said eight trials from six sites throughout the State showed 15 of the 16 crops had a yield response to deep ripping.
The Binnu trial showed deep ripping on metre spacings was less effective (yield improvements) than at 500mm spacings in sandy soils but yield responses on metre spacings could be improved by inclusion plates and use of winged points.
The renaissance of deep ripping throughout WA is thought to be mainly due to farmers wanting to set up paddocks for controlled traffic farming (CTF), hence Mr Parker’s take-home message of staying off deep ripped country.
In another trial, assessing the longevity of deep ripping and inclusion plates under CTF, a key message was the response of lupins to deep ripping with inclusion plates needed to further investigation following negative yield responses.
But there was a real trend towards a positive response in lupins to deep ripping below the depth of the hardpan, though the response was not consistent.
Mr Parker acknowledged fellow researchers Bindi Isbister, David Hall, Glenn McDonald, Glen Reithmuller and recently retired researcher Paul Blackwell for their contributions in trials.