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Start Your Second Grazing Rotation

22 April 2020
Type Media Article

BEEF: Growth is now outstripping demand for most farmers. Look at the regrowth on the first couple of paddocks grazed, are they ready to be grazed again?

It’s now the 22nd of April, the sun is shining, temperatures are up in the mid-teens and the grass growth for this week from PastureBase Ireland was almost uniform at between 48 and 50kg DM/ha/day.

For most, growth is now outstripping demand which is important to start the second rotation, the next part to look at is the regrowth on the first couple of paddocks grazed, are they ready to be grazed again? If so, it’s now time to end the first rotation and start the second if you have not done so already. There are typically three scenarios here:

  1. If you are heavily stocked, any fields that are not grazed to date should be mown for baled silage immediately and fertilised to get them back in the rotation, start grazing the first grazed paddocks.
  2. If you are lowly stocked you could apply an extra bag of fertiliser (30 units of N per acre) to the last un-grazed paddocks and let them in with the first cut silage if it’s going to be cut early to mid-May. Ensure you have your second round of fertiliser out on the grazed ground. These paddocks could also double up as a safety blanket in the east of the country where conditions are getting dry. If growth tightens they could be grazed.
  3. If the un-grazed paddocks have light covers (unlikely), you could graze them and put a bag of fertiliser (30 units N per acre) on the paddocks grazed first this year and let them in with the first cut silage. Like in point 2, these paddocks could also double up as a safety blanket in the east of the country where conditions are getting dry.

The main point is, if your first paddocks are ready to be grazed and you try to finish grazing all your grazing ground by the time you get back to the first grazed paddocks they will be too strong.  This will put you into a situation where you are chasing your tail for the next month to try and graze them out. Cattle will also be eating covers that are too high and therefore won’t be optimising weight gain.

Fertiliser: is the next part of the jig-saw. It’s critically important to have fertiliser out, follow each grazing with 18-30 units/acre of nitrogen depending on your stocking rate. Tables 1 and 2 give example fertiliser programmes for two different stocking rates 1.5 LU/ha or 2.0 LU/ha, they are based on protected urea products. Over the last 8 years Teagasc have conducted trials on protected urea (urea + NBPT), as it is the most cost effective form of nitrogen (14% lower cost compared to CAN).  However, perhaps more importantly protected urea reduces both greenhouse gases and ammonia losses and is the number one technology to meet environmental sustainability commitments. Results also show that protected urea consistently produces grass yields and nitrogen efficiency that match that of CAN based fertiliser programmes.

If you do not wish to use the suggested fertiliser products you can substitute in your own fertilisers based on availability into Tables 1 and 2, using the units/acre as your guide. Always check your Nutrient Management Plan (NMP) for your fertiliser allowances (N & P), if you have not spread your allowance of phosphorous, apply now to maximise growth. Tables 1 and 2 are based on a P & K Index of 2, match your stocking rate first and then check your NMP to get your P and K Index’s and recommended rates. Sulphur should also be incorporated into the fertiliser programme from now on, apply 16 units of sulphur per acre over the next three months).

Drystock Table 1:- Outlines recommended rates of N, P & K kg/ha (units/acre) & fertiliser products (kg/ha,(bags/ac). Farm stocked at 130kg Org N/ha or 1.5LU/ha.  Soil P and K levels assumed to be Index 2 
Advice March April May June /July Sept   Total  Kg/ha(Units /ac)
Product  kg/ha(bags/ac) 63 kg/ha or0.5 bags/ac ProUrea 125 kg/ha or1 bags/ac 18-6-12 +S 125kg/ha or1 bag/ac 18-6-12 +S 50kg /ha or0.4 bags/acre ProUrea 60 kg/ha or0.6 bags/acre 29-0-14+S 
N 112(89) 29 (23) 23(18) 23(18) 23(18) 18(14) 116(92)
P 17(13)   8(6) 8(6) 16(12)
K 40(32)   15(12) 15(12) 8(6) 38(30)
S 10(8)   4(3) 4(3) 2(1.6) 10(8)
Cost €/ha 23 46 46 19 23 €157/ha
ProUrea = Urea 46% + NBPT,  Cost/tonne = €380/t,  ProUrea 40% N & 6% S- €380t/, 29-0-14 + S - €38018-6-12+ 3% S - €370, 18-6-2 - €360. .
Drystock Table 2: Outlines recommended rates of N, P & K kg/ha & (units/acre) & fertiliser products (kg/ha). Farm stocked at 170kg Org N/ha or 2.0LU/ha.  Soil P and K levels assumed to be index 2
Advice March April May June /July Sept   Total kg  /ha (Units/ac)
Product  kg/ha (bags/ac) 165 kg/ha or1.3 bags/ac18-6-12+S 165 kg/ha or1.3 bags/ac18-6-12+S 75 kg/ha or0.6 bags/acPro Urea  80 kg/ha or0.65 bags /acProUrea 60 kg/ha or0.5 bags /acProUrea
N 160(128) 30(24) 30(24) 35(28) 37(29) 28(22) 160(128)
P 20(16) 10(8) 10(8)   20(16)
K 45(36) 20(16) 20(16)   40(32)
S 12(9) 5(4) 5(4) 10(8)
Cost €/ac 61 61 29 30 23 €204/ha
ProUrea = Urea 46% + NBPT,  Cost/tonne = €380/t,  ProUrea 40% N & 6% S- €380t/, 29-0-14 + S - €38018-6-12+ 3% S - €370, 18-6-2 - €360.

Is protected urea more costly?

No, prices in € per tonne fertiliser and € per kg N delivered for the two main fertiliser N types available as per 21st April, 2020.

Fertiliser N ProductN content (%)Cost per tonne (€)Cost/kg N (€)
Protected urea 46% 370 0.80c
CAN 27% 250 0.93c

Note: Complete a farm fertiliser plan to determine max. N & P allowances as per nutrient legislation for your farm. Consult with your advisor on grass silage fertiliser programmes.