Balanced nutrition in Brassica napus production with emphasis on S fertilizer requirements

Transcription

1 Balanced nutrition in Brassica napus production with emphasis on S fertilizer requirements Rob Norton. Regional Director ANZ Thomas Jensen, IPNI Northern Great Plains Vladimir Nosov, IPNI Southern & Eastern Russia Better Crops, Better Environment through Science ARAB 17, Wagga Wagga, August 2011

2 Why S and why now? Less use of high S fuels so less S from atmosphere. Use of high analysis fertilizers containing little incidental S Increased crop yields creating a higher S offtake. Slower organic matter turnover with conservation tillage Fewer S-containing pesticides t/km 2 McNeill et al, 2005, Soil Use & Management

3 S deficiency in Australia History of S deficiency in pastures. Deficiencies in canola first seen in NSW at Lockhart. Soils naturally low in S & OM. Since 1990, reduced use of single super clear trend to AP s High demand for S by canola. Sulphate is mobile leachable.

4 S removals and S balances Current fertilizer rates would indicate input of 1-5 kg S per ha Offtakes differ among crops (Reuter & Robinson) Crop N P K S S % Canola 2 t/ha Wheat 3 t/ha Crop S content Cv% Data Canola % Khan et al., IPL Dahlen Wheat % NVT SE Aust.

5 N % Grain Nitrogen to Sulphur Ratios a retrospective for balanced nutrition S RESPONSIVE S UNRESPONSIVE Inadequate N N & S CO-LIMITED ADDED N OR S WILL CORRECT TO 17:1 Slope ~7: Randell et al, 1981, AJAR, 32, S %

6 Soil S levels ANRA Audit 2001 Nationally 11% < 5 mg/kg KCl-40 (mg/kg) Crop Pasture <8 52% 43% % 30% >12 28% 27% New South Wales 25% < 5 mg/kg Victoria 3% < 5 mg/kg Draws on data from mid-1990 s 2010 Requires Soil S revision test values and (top review 10 cm) current for Victoria, IPNI ANZ South project Australia, New South Wales (~1200 tests)

7 Soil S levels KCl (Pre-sowing ie before May 2010) Location and Soil Type KCl 40 Wheat (mg/kg) KCl 40 Canola (mg/kg) <3 3 to 5 >5 <12 >12 Harden Red & Brown Loams 11% 33% 56% 80% 20% Horsham Grey & Brown Clay Loams 23% 18% 59% 68% 32% Maryborough Red & Brown Clay Loams 0% 8% 92% 74% 26% Cummins Red & Brown Sandy Loams 12% 44% 44% 74% 26% Moree Gray &Brown Clay/Clay Loams 17% 20% 63% Dalby Gray &Brown Clay/Clay Loams 15% 23% 62% Emerald Gray &Brown Clay Loams 27% 19% 54% Gunnedah Gray &Brown Clay Loams 10% 26% 63% Soil depth 0-10 mobility of S in profiles, maybe need a deeper soil test as routine when request nitrate, also request sulphate. Role of organic sulphur should the budget include mineralised S.

8 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) R Gelderman, SDSU J Laycock, IPL C Dowling, Backpaddock P/L Share or similar mixing point (7.5 cm spread) Light (sandy loam) texture Medium (loam/clay loam) texture Heavy (clay) texture

9 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

10 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.

11 Topdress S in-crop ammonium sulphate, potassium sulphate, ATS Where the plant can get it Root zone control release rates to avoid leaching In synchrony with plant demand canola can recover from nutrient stress eg Canola S applied Kg/ha Sowing 5-6 Leaf Buds Visible Stem Elongati on LSD Hocking et al., 1996

12 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

13 Summary Care with S and N in-furrow with canola especially light soils, dry conditions, 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.