GMP 4 : Nutrient and Cost Analysis

GMP 4 : Nutrient and Cost Analysis

Chicory as Fodder Crop with Mark Dibley

Perrin Ag Consultants assessed Mark Dibley’s experience with introducing chicory as a fodder crop instead of turnips. The analysis below summarises the nutrient savings, impacts on profit and the wider farm system, risks and additional on-farm skills required to implement this nutrient practice.  
Nutrient losses

OVERSEER 6.2.3 was used to model the proposed use of chicory as an alternative to a typical leafy turnip summer forage crop. This was a direct substitution of the 14ha of leafy turnips replaced with 14ha of pure chicory (no clover content) and managed accordingly.

OVERSEER is still unable to model chicory as a forage crop, so current protocols dictate the chicory is modelled as a “Rape” crop.

Chicory crops will, on average, tend to have similar total forage yields to a leady turnip crop but, as a multi-graze crop, this yield will be spread out over a longer time period.

Bay of Plenty Regional Council (BOPRC) protocols for OVERSEER use require average yields to be used for all forage crops. This, in our, view tends to underestimate the typical crop yields we see/measure in practice here in Rotorua. As a result, an “average” tonnage of 8t DM/ha was used for both the turnip and chicory crops in OVERSEER, but a yield of 10t DM/ha was used when the farm system was modelled in Farmax Dairy software.

Modelling in Farmax Dairy indicated an increase in annual milk solids production of 1,344kg MS could be expected from replacing the turnips with the chicory. This production impact was also modelled in OVERSEER 6.2.3.

In total, whole farm system N losses decreased by 255kg N and 1kg P from replacing the turnip crop with a chicory crop. Based on the modelled farm’s effective pastoral area, this was a decrease of 1kg N/ha/year.

  Turnips Chicory
Establishment Conventional seed-bed preparation (cultivation) Direct-drilled
N fertilser 33kg N/ha at sowing 92 kg N/ha in a single post -establishment side-dressing – 125 kg N total 18 kgN/ha at sowing 128 kg N/ha in four post -grazing side-dressing – 146 kg N total
Grazing Allocated at 4kg/cow/day in single defoliation event over Jan/Feb Allocated at 2.5 kg/cow/day (say 4kg/cow single herd) in multiple defoliation events over Dec/April
Re-grassing Occurs in March. Realistically required conventional establishment Occurs in early April. Direct drilling would be appropriate

The reduction in N losses are likely to have occurred from the change in cultivation practices, the uptake of urinary N from the re-growing crop, the lower crude protein content of the chicory and a more even spread of N fertiliser applications. Any potential diuretic effect on the frequency of cow urination or the potential deeper root interception of the chicory plant are not taken into account in OVERSEER.

Economic modelling

Partial budget analysis was completed to calculate the economic impact of this GMP. Crop establishment/husbandry costs were similar for both crops (including all N fertiliser applications), but the improved utilisation and slightly higher feed quality of the chicory resulted in the chicory crop lifting milk production by 8.7kg MS/ha. At an average milk price of $5.80/kg MS, this system change, as modelled, delivers a net benefit of $11,173.

GMP partial budget – Chicory vs Turnips

Increased Revenue Increased Costs
Additional milk Solids at $5.80/kg MS $7,795 Cost of chicory Crop $16,503
Decreased Costs Decreased revenues
Cost of turnip crop $16,755 None $  –
Total Benefit $24,550 Total Cost $16,503
Net Benefit $8,047

This is equivalent to $6,857/kg N loss reduction.

Key risks

The major system impact of replacing turnips with chicory is the distribution of the feed produced. Leafy turnips are generally available for grazing 45-60 days after sowing, but have a limited consumption window (30+-45 days) before feed quality rapidly declines. As a result, per cow allocation tends to be between 3-4kg DM/cow/day and crops are finished and available for re-sowing early in the autumn, allowing new pasture to be established for grazing in May. The moderate forage allocations (20-25% of diet) allow pasture to be substituted, the grazing round to be extended and pasture cover pushed out (maintained) further into the summer period.

With the chicory (as modelled utilising the same sown area) a lesser average ration (2.5kg DM/cow/day) has to be offered to fit in with the 17-25 day grazing cycle of the crop. In practice this means that for the same area sown, a lesser number of cows will graze (i.e. one herd rather than both herds). While this feed is available from mid-late December through until early April, the lower daily allocation per total cow means that more pasture has to be offered to the cows, driving pasture covers lower. While our modelling indicates this practice is still feasible, it does introduce a degree of risk in drier conditions if pasture covers approach 1,800kg DM/ha by the end of February (although we note this commonly occurs in local farm systems).

The longer feed availability also means that establishment of new pasture occurs 4-5 weeks later than with a conventional turnip crop (if similar yields are to be achieved) which means that new pasture is not going to be able to enter the grazing round until late May. This is likely to be offset by the extended summer forage availability allowing autumn pasture covers to be built up earlier.

Additional skills required

Having less feed to allocate to cows per day with the chicory crop will invariably mean that the farm will stay on a faster grazing rotation over summer than might normally be the case if summer production levels are to be maintained. This faster round realistically requires closer monitoring of pasture cover and residuals in order react to unexpected slowing of pasture growth rates.

Implications for the wider farm system

Outside of the issues discussed above, cow body condition should be more easily maintained over the summer period with the replacement of turnips with chicory. Turnips tend to have high levels of crude protein that when fed at higher rations can lead to a loss in cow body condition, despite their high energy content and the often lower protein content of summer pasture. This risk would be lessened by replacing them with an equivalent quality (energy content) feed with lower protein levels, like chicory.