Best management for N & S in canola and wheat Rob Norton - - PowerPoint PPT Presentation

Best management for N & S in canola and wheat

Rob Norton http://anz.ipni.net

Nutrition – the way forward

• You get nothing for nothing…….

– If produce is removed, nutrients go with it – if not replaced, then the soil reserves go down. It is soil not the “Magic Pudding”.

• Address the limiting factor……

– What is limiting production – until that is addressed, then no extra

• response. Its no good pumping up the tyres if the tractor is out of

fuel.

• There are no silver bullets…….

– If something sounds too good to be true – then it probably is.

Where to start you nutrition program: Make a realistic estimate of demand…..

MSF N site in July 2011 – Yield Prophet estimates

Aim to at least balance output with input

• Demand for ~N twice the offtake, S about offtake.
• 25 mm rain gives ~ 0.3 t/ha canola or 0.45 t/ha wheat
• 25 mm rain means 21 kg N for canola, 18 kg N for

wheat.

Why canola needs more S than wheat

• Wheat 10% protein

15:1 N:S

• Canola 20% protein

7:1 N:S

N & S deficiency in wheat

Sulfur

H Burns, NSW DPI T Jensen, IPNI A Johnson IPNI

Why S?

MAP/DAP

Fertilizer %P %S Superphosphate 8.8 11.0 TSP 20.7 1.0 DAP 20.0 1.6 MAP 21.9 1.5

So what to do?

• Select the right source/product, apply

it at the right rate, and at the right time and in the right place!

• 4 Rights of nutrient management.

The Right Rate - Soil test

Crop Deficient Marginal Adequate Pasture <5 5-10 >10 Canola <12 12-18 >18 Wheat <3 3-5 >5 KCl-40 (mg/ kg) Crop Pasture <8 52% 43% 8-12 20% 30% >12 28% 27%

2010 Soil S test values (top 10 cm) for Victoria, South Australia, New South Wales (~1200 tests)

Blair 1993 P&S

Problem with leaching & soil tests

• Sulfate mobile
• Sulfate supplied

– Mineralisation OM – Oxidation S

• Improved tests;

– Appropriate depth – Take account of some part of the

• ther S sources.

Soil Colloid SO4

= Leaching

Strategies for S

• Spread out the need through the whole rotation

– Higher S rates in the cereal phase (more tolerant of seed placed fertilizer) – Canola/Wheat/Barley – use 10/15/15 to meet total demand. – Depends on soil type/S mobility – Use high rates up front (eg gypsum) – Elemental S

• +Bentonite

Improving S nutrition

To apply 20 kg S/ha

• Gypsum (~200 kg/ha)
• Surface applied
• Variable quality
• Cheap (?)
• Ammonium sulphate (100 kg/ha)
• Fertilizer damage to seedlings (machinery)
• See http://anz.ipni.net/anz0042-en

Opener ¡type ¡and ¡row ¡spacing ¡ (cm)

Inverted ¡T ¡or ¡similar ¡narrow ¡point/opener ¡ (2.5 ¡cm ¡spread)

Share ¡or ¡similar ¡mixing ¡point ¡(7.5 ¡cm ¡spread)

15 22.5 30 15 22.5 30 Light ¡(sandy ¡loam) ¡ texture ¡

50 ¡ 35 ¡ 25 ¡ 150 ¡ 100 ¡ 75 ¡

Medium ¡(loam/clay ¡ loam) ¡texture

75 50 40 230 150 110

Banding fertilizer away from seedrow

• Particularly important for N and S
• (includes MAP)
• Band fertilizer away from seed

– Band 2-3 cm away – Side or Side & Below – Mid-row band

• P/K source in seed row.

Right place & right time

• Ammonium Sulfate, Potassium sulfate
• Where the plant can get it –

– Root zone – control release rates to avoid leaching

• In synchrony with plant demand – ability to recover from

nutrient stress – eg Canola

S applied Kg/ha Sowing 5-6 Leaf Buds Visible Stem Elongatio n

10 1.73 1.62 1.56 1.41 LSD 40 2.15 2.26 2.11 2.19 0.43

Hocking et al., 1996

Right product

Product N P K S Superphosphate 8.8 11 MAP 10.0 21.9 1.5 DAP 18.0 20.0 1.6 Triple Superphosphate 20.7 1.0 Ammonium Sulphate 20.2 24 Sulphur Bentonite 90 Sulphate of Potash 41 18

• Deliver sulfate to the rootzone at the right time
• A range of S fortified products – sulfur coated urea, sulfur

coated MAP & DAP.

• Usually coated with S0 (elemental) which requires oxidation to

release sulfate & it all happens at once!

• Nutrient co-location can be important (P/S – Friesen 1989)

Alternative sources of S

Particle Size µ % S oxidised 2 weeks 4 weeks <75 80 82 75-125 61 81 125-175 36 68 175-400 15 36 400-840 5 14 840-2000 2 5 2000-4000 1 2

• S0 oxidation rapid with fine

particles

– Good for sulphate release – Bad for handling

• Two new processes that

incorporate S0 into existing products at manufacture 12:18:0:10 N:P:K:S Up to 14% S 50:50 S0:SO4

80 kg/ha SOA (17N, 19S) 50 kg/ha Urea (23 N)

Ammonium Sulfate Gypsum + urea 30 N + 35 S

Canola response to AmS v U+G

Source Yield P2009 Yield P2010 Yield H2010 AmS 1.55a 1.93a 2.03a U+G 1.08b 1.93a 1.67ab Nil 0.90b 1.72b 1.29b

Soil Test KCl40 Pira 2009 2.5 Pira 2010 2.7 Horsham 2010 1.5

Ammonium sulphate

• Traditional fertilizer – seen as a better S source than

gypsum.( Root Zone acidification, Coplacement of N/S, Reduced N loss).

• As a plant fertilizer – not enough N – looking at Urea/

Ammonium Sulfate fluids or co-granulated UAS fertilizers, compared to UAN/ATS fluids

N losses via volatilization:

Turner et al. 2012 (Nutrient Cycling in Agroecosystems,93, 113-126)

• 2 expts in Wimmera

– 23% N loss from urea – 12% N loss from UAN – 12% N loss from AS – Rain 9 DAF – 13% N loss from urea – 3% N loss from AS – Rain 1 DAF

Summary

• Make a realistic yield estimate
• Deep soil test
• Care with S and N in-furrow with

canola – especially light & dry soils, wide rows.

• Compared to cereal crops, canola requires a

greater supply of S – N:S 7:1 canola; 15:1 wheat

• Applying all the required S in the seed-row for

canola is difficult because of excess N coming from the ammonium phosphate and ammonium sulphate portion of a possible seed-row blend.

• There are alternative ways to supply sufficient S

and avoid excess N in the seed-row.

New/Old Products

• Evidence from Trials

– Appropriate controls – Replicated – Randomised – Repeatable – Reasonable

• Mass balances?
• Magic or special?
• Laws of physics/chemistry
• Test it yourself, be sceptical –

its your $ and your reputation.

• Ask “How do you know that?”