Up to double drymatter production possible

Date: 2009-02-01 | Category: Resources

Well established new pastures will yield 20-100% more drymatter production compared to the previous pasture, a benefit analysis report shows.

The greatest gain will be made when the new pasture is replacing a pasture dominated by weeds and unwanted grasses and has been identified as performing poorly. 

Renewed pastures were compared to improved resident pastures in a series of experiments at six sites representing 15% of farmed land nationwide in the 1980s.

In these experiments a resident control was included, and variations in fertiliser and grazing management were applied to all treatments.

Measurements were made over 5-6 years and included total pasture production, botanical composition and persistence of sown species.

In summary the results showed the resident pastures performed consistently below the average production of the renewed pastures by approximately 1000kg DM/ha regardless of the average production of the site.

However, rainfall levels caused the most variance - the resident pastures performed similarly to renewed pastures when rainfall at a site dropped below 850mm annually.  When rainfall reached 1400mm annually, drymatter production of the renewed pastures increased significantly to be 1500kg DM/ha above that of resident pastures.

The annual drymatter production of unimproved pasture documented at one site was 4500-5500kg DM/ha while the improved resident (fertiliser plus subdivision) produced between 7850 and 10,500kg DM/ha.

An increase due to pasture renewal of 8950 and 12,800kg DM/ha was recorded at this site.

Renewal of hill country pastures with cocksfoot showed that an increase in annual drymatter production of between 1300 and 1500kg DM/ha (approximately 18%) above the resident pasture can be achieved depending on phosphate inputs.

Establishing clover into dry North Canterbury hill country increased pasture yield on sunny faces from 2100-1390kg DM/ha/year in improved and resident pastures respectively.

The increase in production on shady faces was much greater, going from 1380-4190kg DM/ha.  The introduction of grasses on the shady sites increased the total production to approximately 4800kg DM/ha.  In all cases, fertiliser was added. 

Over-sowing clover is often used as a means of improving hill country.

Results have shown that this practice can increase clover production, and this increase is greater when phosphate deficiencies are corrected. 

Several studies have indicated increases in drymatter production from pasture renewal on dairy farms ranging from 17-35% when compared to resident swards.  A more comprehensive recording of pasture renewal on-farm showed a significant increase of 12-15% in drymatter production.

Data from the Woodlands Research Station shows a relatively consistent increase in daily pasture growth rate of a recently renewed pasture compared to a 10 year old pasture.  Total annual production was 1270kg DM/ha greater on the renewed pasture after the initial establishment period (figure 1) .

Interestingly, the report says for an irrigated pasture in mid Canterbury the establishment of a new pasture by direct drilling resulted in an average annual yield of 13,100kg DM/ha over the following three years, a decrease of 2100 kg DM/ha compared with the control.

Much of the variation between positive and negative results comes from the establishment period and grass grub attack during year three.

Recently, Meat & Wool NZ's Pasture Plan programme (2006) provided data on pasture production around New Zealand.

This programme reports several farmers have chosen to measure the difference between recently renewed pastures and resident pastures. 

Results ranged from an advantage of between 10 and 15kg DM/ha/day in early to mid-spring only, to 2-3 times more pasture throughout the year.

Published courtesy Country-Wide - March 2008. An edited extract from AgResearch's Literature Review for PRCT.

PRINTABLE VERSION

TOP