Fertiliser for oats: grain, hay and grazing oats

Do oats need fertiliser?

Yes. DPIRD says oats were traditionally a low-input crop on poorer paddocks, but higher-yielding grain and hay varieties and tighter quality markets mean nutrition now matters. Like wheat and barley, oats grow poorly on WA's sandy soils without added nutrients.

• Major nutrients: nitrogen (N), phosphorus (P), potassium (K) and sulphur (S). Trace elements: copper, manganese, molybdenum and zinc (DPIRD).
• Oaten hay removes a lot of all the major nutrients, and carting it off makes the soil more acidic over time (DPIRD).
• Incitec Pivot says a good forage oat crop can need more nutrition than prime hard wheat.
• Northern Tablelands Local Land Services (NSW) names P, S and N as the most common limiting nutrients for grazing oats, and says dual-purpose crops need more.

Nitrogen: rate and timing

• DPIRD's rule of thumb for WA is 40–80 kg N/ha, adjusted for season and variety. Dwarf varieties need about 20% more.
• In dry seasons the response to N is often poor. DPIRD says a foliar N spray may be a better option than granular in drier years.
• In wet seasons N can leach on sands, so delay or split it. For grain, DPIRD has found profitable responses to N up to 10 weeks after sowing.
• Forage oats (Incitec Pivot): 40–100 kg N/ha before planting is generally enough, budgeted from a soil test. Then topdress about 50 kg N/ha ahead of rain after the first grazing, or after each grazing under irrigation or high rainfall.
• Set a protein target for forage. Incitec Pivot gives 12–14% dry matter protein for young stock and lactating cows, and 8–10% for maintenance or fattening older animals.

Urea spread on the surface can lose N to the air; Incitec Pivot cites losses of 5.4–19% in northern soils. Read how much N urea loses and urea on pasture: when to apply. Options include Granular Urea, Gran-Am (N plus S) and Green Urea NV; compare urea and Gran-Am.

Hay oats: watch N rates and nitrate

• DPIRD says too much N lowers hay quality: more stem fibre, less water-soluble sugar, and a higher lodging risk.
• Apply any late N between tillering (Z25) and stem elongation (Z31). Later than Z33, nitrate builds up in the hay, which many hay markets will not accept.
• Split N applications appear important for hay (DPIRD).
• For grazing crops, Incitec Pivot warns nitrate can build up in slow-growing oats after frost, cold cloudy weather or waterlogging, mostly in the bottom third of the stem. Graze actively growing crops.

Phosphorus and seed safety

• Incitec Pivot says P gives the biggest dry matter response in forage oats and must be near the seed at planting; foliar P is not a proven fix.
• Its data suggest oats respond where Colwell P is below 35 mg/kg. The guide rate for forage oats is 8–20 kg P/ha at planting.
• Starter options: MAP, Granulock Z (with zinc) or SuPerfect (with sulphur). See MAP vs DAP.
• Do not put too much N with the seed. As a guide in an average season, Northern Tablelands LLS says up to 20 kg N/ha can go with the seed at 7-inch (about 18 cm) rows; it varies with soil, moisture and soil disturbance.

Potassium, sulphur and trace elements

• Potassium: in WA trials oat hay and grain needed at least 70 kg K/ha to reach their best yields, and on soils below Colwell K 80 mg/kg a lack of K limited the response to N (DPIRD).
• Incitec Pivot says hay and silage paddocks are especially prone to K deficiency. It suggests muriate of potash drilled in narrow bands 4–6 weeks before planting, never with the seed. See muriate of potash and fertiliser for hay.
• Sulphur: where soil S is below 5 mg/kg, Incitec Pivot suggests 20–30 kg S/ha as sulphate, for example Gran-Am or SuPerfect. Browse sulphur fertilisers.
• Zinc: in northern alkaline soils, zinc is the key trace element; a zinc-fortified starter at planting is the best strategy (Incitec Pivot). See zinc deficiency in wheat.

Start with a soil test (see reading a soil test) and a tissue test if a deficiency is suspected. Always check with your agronomist before acting.