Best management for N & S in canola and wheat. Rob Norton

Transcription

1 Best management for N & S in canola and wheat Rob Norton

2 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.

3 Where to start you nutrition program: Make a realistic estimate of demand.. MSF N site in July 2011 Yield Prophet estimates

4 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.

5 Why canola needs more S than wheat Wheat 10% protein 15:1 N:S Canola 20% protein 7:1 N:S

6 N & S deficiency in wheat

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

8 Why S? MAP/DAP Fertilizer %P %S Superphosphate TSP DAP MAP

9 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.

10 The Right Rate - Soil test Crop Deficient Marginal Adequate Pasture < >10 Canola < >18 Wheat <3 3-5 >5 KCl-40 (mg/ kg) Crop Pasture <8 52% 43% % 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

11 Problem with leaching & soil tests Soil Colloid - - = SO 4 Leaching Sulfate mobile Sulfate supplied Mineralisation OM Oxidation S Improved tests; Appropriate depth Take account of some part of the other S sources.

12 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

13 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 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) Light (sandy loam) texture Medium (loam/clay loam) texture

14 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.

15 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 LSD Hocking et al., 1996

16 Right product Deliver sulfate to the rootzone at the right time Product N P K S Superphosphate MAP DAP Triple Superphosphate Ammonium Sulphate Sulphur Bentonite Sulphate of Potash A range of S fortified products sulfur coated urea, sulfur coated MAP & DAP. Usually coated with S 0 (elemental) which requires oxidation to release sulfate & it all happens at once! Nutrient co-location can be important (P/S Friesen 1989)

17 Alternative sources of S S 0 oxidation rapid with fine particles Good for sulphate release Bad for handling Two new processes that incorporate S 0 into existing products at manufacture Particle Size µ % S oxidised 2 weeks 4 weeks < :18:0:10 N:P:K:S Up to 14% S 50:50 S 0 :SO 4

18 50 kg/ha Urea (23 N) 80 kg/ha SOA (17N, 19S)

19 Ammonium Sulfate Gypsum + urea 30 N + 35 S

20 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 Pira Horsham

21 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

22 N losses via volatilization: Turner et al (Nutrient Cycling in Agroecosystems,93, ) 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

23 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.

24 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?