The question here is whether to sow on the row or within the inter-row. Sowing on the previous years row instead of the previous years inter row has been shown to enhance soil water content although it may leave you open to disease threats such as crown rot. This article will look to weigh up the benefits of both systems.
#1 Phosphorous accumulation
Due to a series of poor years there has been an accumulation of phosphorous within soil profiles. In addition, the use of knife points, disc seeders and wider row spacings has resulted in changes in the spacial distribution of phosphorous with specific reference to concentration within the inter-row. The changes in the spacial distribution could either positively or negatively impact on crop performance, depending on the crop in question. In conditions where a fertiliser tolerant crop is sown closer to the starter fertiliser band the crop may benefit from the ease of uptake. Although if you have a relatively sensitive crop such as canola the close proximity of the start-up fertiliser may depress early growth of the crop.
There is a relationship between the responses of cereals and broadleafs to row spacings and the interaction with plant populations. As row spacing and seeding rate increases the distance between seeds declines. This can impact on the final germination percentage for the crop. The trial data below from Temora and Condobolin indicates that as seeds were sown closer together the establishment percentage significantly declined.
Relationship between P and row spacings
Figure 2 outlines the effects of row spacings and fertiliser concentration. For a rate of 50kg/ha of MAP increasing the row spacings from 200 to 500 mm, there is an increase from 40-100 granules of MAP per metre row.
Figure 2: Effects of row spacing on the amount of starter fertiliser (50kg/ha MAP applies at all spacings) within the row
A trial was conducted at Condobolin under three separate row spacings (170, 300 and 430mm). At the 170 and 430 mm spacings, yield increased with phosphorous up to 8kg P/ha and then leveled off whereas at 300 mm, yield decreased at phosphorous levels of above 12 kg P/ha.
A row spacing by phosphorous trial was setup in order to look at the difference between sowing on-row and sowing inter-row.
The results concluded that if you are on wide row spacings and you inter row sow next year it will take longer for the plant to reach the available phosphorous although not as long in the second year.
#Off row seeding and moisture
With the adoption of autosteer technologies growers are now able to accurately place the seed wherever they see fit. In Western Australia where non-wetting soils are a major impediment to good crop establishment, minor improvements in soil wetting around the seed can lead to major improvements in crop establishment. Wetting around the seed can be done achieved naturally by the previous year’s standing stubble.
Studies indicate that under no tillage, old and current crop rows provide pathways for water movement within the soil profile. Stubbles leave behind crowns, root channels and bio pores that are all capable of trapping moisture within the stubble zone. These factors are capable of improving the soils wetability.
The research shows that in relation to root penetration and moisture availability it is much better to sow on the row. If a paddock has experienced issues with crown rot in the past then sowing on the row will be placing the seed within the innoculum supplied by lasts years crop.