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Phosphorus Nutrition Of Corn. Outline – P Nutrition of Corn Changes in root system development over the season Impacts on attainable yield potential Requirements.

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Presentation on theme: "Phosphorus Nutrition Of Corn. Outline – P Nutrition of Corn Changes in root system development over the season Impacts on attainable yield potential Requirements."— Presentation transcript:

1 Phosphorus Nutrition Of Corn

2 Outline – P Nutrition of Corn Changes in root system development over the season Impacts on attainable yield potential Requirements through growth stages Placement options Soil test levels and corn response to P inputs Profitability of P fertility management

3 36 Days 8 Weeks Mature Source: Weaver, 1926 Corn Root System Development

4 The first roots grow from the seed, but the main root system starts from the first node above the seed. Planting depth affects the depth of the seed roots, but the depth of the initiation of the main root system is the same, regardless of planting depth.

5 Fertilizer P 2 O 5 Rate, lb/A Roots colonized at 6-leaf stage Corn dry matter at silking, tons/A 021% % %5.2 Mean of 2 years, 1997/98, Quebec. Soil test P (Mehlich 3) was 65 to 87 ppm. Adapted from Liu et al., 2002 Effect of fertilizer P on corn mycorrhizae. Mycorrhizae “Fungus-root” Extend to absorb P from more soil Decline with increasing P fertility, fallow

6 P supplied Shoot V1 Shoot V3-V4Kernel,Yield, up to V3-V4%#/plantbu/A High Medium Low All treatments received high P after V3-V4 (ISU) Mean of 2 years, Source: Barry & Miller, 1989 Early P Nutrition – Outdoor Hydroponics

7 High-yield corn (307 bu/A) Source: Karlen et al., How a Corn Plant Takes Up Phosphorus

8 Source: Mengel & Barber, 1974 Corn grown in silt loam at Purdue Agronomy Farm, Indiana. Silt loam soil; planted May 5, 1971; final grain yield 187 bu/A. Nutrient Uptake in Corn Versus Stage of Growth Days after planting Total P 2 O 5 uptake, lb/A 75% Silking Maximum uptake rate 2 45 dap Maturity

9 Nutrient Uptake: Total uptake ~0.55 lb P 2 O 5 per bushel of grain yield Silage harvest removes lb P 2 O 5 per ton at 65% moisture

10 Source: Heckman et al., lb of P 2 O 5 per bushel Nutrient Removal in Grain:

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12 P Deficiency in Corn Seedlings

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14 Can apply large amounts conveniently Ideal for building soil fertility Minimizes risk of fertilizer injury On fields of low fertility, banded starter P may not be adequate for maximum yield Combinations of broadcast and band applications produce the highest yields on low testing soils Why Broadcast?

15 Overwhelms soil fixation capacity Places nutrients near the seedling –Roots intercept early and proliferate near the band –Including ammonium-N, slows P fixation and lowers pH near the root to improve both P and micronutrient availability Favors the crop over the weeds Keeps nutrients away from the surface –Reduces runoff P concentrations Band Application

16 PP 2 O 5 applied,Grain yield, bu/A applicationlb/A average TillagemethodHigh P siteLow P siteHigh P siteLow P site One-passNone Starter Broadcast Fall band Strip-tillNone Starter Fall Band Source: Randall, et al., 2001 Placement Options

17 Source: G.W. Rehm, Minnesota Fertility Affects Impact of P and K Placement

18 Source: Bates, 1971; Richards, et al., 1985 Ontario research from 1960s and 1970s (52 site-years) showed that 50 lb/A with the seed: –Increased yield by zero to 2.9% –Delayed and sometimes reduced emergence –Hastened time to silking –Decreased grain moisture at harvest Placing P With the Seed

19 P 2 O 5 rate,Corn yield, 1 lb/Abu/A Mean of two hybrids at each of two Ontario sites; seed-placed Mean of three Ontario sites 3 Mean of three products: , , Corn yield, 2 bu/A Rate, lb P 2 O 5 /A Liquid 3 Granular MAP, Source: Lauzon et al., 1995 Seed Placement: Small Amounts, Liquid or Granular

20 Source: Bundy, 2001 Late Planting of Full Season Corn Increased Response to Starter in Wisconsin

21 SymbolCompoundFormulapH TSPmonocalciumCa(H 2 PO 4 ) phosphate MAPmonoammonium NH 4 H 2 PO phosphate TPP 1 triammonium(NH 4 ) 3 HP 2 O pyrophosphate DAPdiammonium (NH 4 ) 2 HPO phosphate 1 Main P form in liquid P Sources and Solution pH

22 Soil test Probability of response to P category MN-SD-NDON Very low > 80% Low 60-80%75% Medium 40-60%55% High 20-40%25% Very high < 20%< 25% Category definitions vary among laboratories Soil Test Interpretation: Index of the Likelihood of Crop Response

23 Source: PKMAN Version 1.0, PPI Corn Response to P

24 Data source: Webb et al., 1992 (Iowa) Mining P Reduces Soil Test P 298 lb P 2 O 5 in lb P 2 O 5 in Bray P-1 (ppm)

25 Data source: Webb et al., 1992 (Iowa) Residual Effect of P 298 lb P 2 O 5 in lb P 2 O 5 in Corn grain yield, bu/A

26 Zn deficiency impairs plant P regulation Either high soil P or large amounts of applied P can induce Zn deficiency if soil Zn is low and no Zn fertilizer is applied P2O5P2O5 ZnYieldLeaf tissue lb/A *bu/AP, %Zn, ppm Data source: Adriano and Murphy * P and Zn band-applied Phosphorus and Zinc

27 Continuous application of very high rates of P does not always induce greater Zn deficiency (Mallarino, 1995) Olsen soil test P, ppm Fertilizer P 2 O 5 applied, lb/A Corn seedling Zn, ppm Adapted from Shang & Bates, 1987 Phosphorus and Zinc

28 Irrigated continuous corn, Kansas, 30 years data, N rate at MEY: with P = 159 lb/A without P = 145 P increased N use efficiency instead of greatly increasing N fertilizer demand Source: Schlegel et al., 1996 Effect of N and P on Corn Yield N rate, lb/A Yield, bu/A with P without P

29 Source: Schlegel et al., 1996, 30 year average Corn $2.30/bu, N $0.15/lb, P 2 O 5 $0.24/lb; other costs $240/A The economic optimum N rate with P is 159 lb/A. P increased profit by about $120/A at this rate Effect of N and P on Net Revenue N rate, lb/A Net revenue, $/A with P without P

30 Source: Schlegel et al., 1996; 30 year average At optimum N rate, P reduced residual nitrate by 66% P Reduces Residual Soil Nitrate and Potential for Nitrate Leaching After 30 Years N rate, lb/A Soil NO 3 -N in upper 10 ft, lb/A with P without P

31 Phosphorus Hastens Corn Maturity

32 Corn, $2.50/bu; N, $0.15/lb; P 2 O 5, $0.24/lb Calculated from Dhuyvetter and Schlegel Phosphorus Hastens Maturity and Lowers Drying Costs, Adding to Return to P Fertilizer nitrogen rate, lb/A Net return to 40 lb P 2 O 5 /A, $/A Drying cost reduction Yield response income

33 Summary - P Nutrition of Corn Roots must grow to where the P is, since P is nearly immobile in most soils Seedlings provided with high P develop higher attainable yield potential Uptake of P continues through the season Placement near the seedling often boosts yield. Corn response to P depends on soil test level P fertility management is key to profitability and efficient use of N

34 International Plant Nutrition Institute (IPNI) 655 Engineering Drive, Suite 110 Norcross, GA Phone: ; Fax: Reference 06128


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