Fertility management in soybean

Transcription

1 Fertility management in soybean Dorivar Ruiz Diaz Soil Fertility and Nutrient Management In-depth Soybean Schools 2014

2 Overview Considerations for soil sampling and testing. Considerations for N, P and K fertilization. Update on secondary and micronutrients for soybean in KS.

3 The first step in fertility management is soil testing In Kansas the greatest potential return to fertilizer dollars in soybean is from P, K, and some micros depending on the region (i.e. Fe). Sulfur becoming an issue for some crops, currently no clear response on soybeans. Optimum soil ph is essential for soybean. ph, P and K have reliable soil tests to measure nutrient availability and predict fertilizer/lime needs.

4 Where to take samples Sampling areas should be easily defined and treatable with equipment available Soil sampling should try to capture known differences in nutrient levels These differences can be due to past management, natural soil variability, topography or removal with yield. Consider the potential benefits and cost when deciding how and where to sample

5 Nutrient Removal in the field Crop Unit P2O5 (lb) K2O (lb) Corn bushel Grain Sorghum bushel Wheat bushel Sunflowers pound Oats bushel Soybeans bushel

6 Decision Based - STP Soil Test P (M3 ppm) (gpa)

7 Combine layers of information Soils and topography Past management Yield monitor data Grid soil samples Manure applications

8 Proper soil sampling Consistency in depth of sample. 0-6 for immobile nutrients 0-24 for mobile (N, Cl, S). 0-3 only for ph evaluation in No-till systems Appropriate number of subsamples (12-20 subsamples). Be consistent on sampling time. Late fall, winter and early spring-november through March are good.

9 Nitrogen deficiency in soybean Cody Miller, 2010

10 Nitrogen deficiency in soybean N rate Average (lb/a) Yield (bu/a) 0 28d 18c 23d 30 37c 23b 30c 60 42b 26b 33cb 90 43b 26b 34b a 29a 39a Mengel and Ruiz Diaz, 2012

11 Nitrogen deficiency in soybean Mengel and Ruiz Diaz, 2012

12 Effect of N Fertilizer and Inoculation on Soybean N rate (lb/acre) Yield (bu/acre) Inoculation Yes No 60a 57b Ruiz Diaz et al, Crop Sci. 49:

13 Phosphorus: Soybean yield response MAP TSP Grain Yield (bu/acre) STP: 9 ppm P (lbs/acre) Ruiz Diaz, 2010

14 Soybean response to direct application of P Treatment Early Biomass Yield No P d Residual c Residual bc Residual bc Residual a D. Mengel, 2010

15 Annual vs. Biennial: Phosphorus fertilization -Ashland Soybean yield (bu ac -1 ) Control Residual Direct Residual + Direct b ab ab a Ashland P < Control Before corn Before soybean Before Corn+Soybean 40 lbs P2O5 before corn Arns and Ruiz Diaz, 2012

16 Annual vs. Biennial: Phosphorus fertilization Silver Lake Soybean yield (bu ac -1 ) Topeka P > 0.34 Control Residual Direct Residual + Direct 55 0 Control Before corn Before soybean Before Corn+Soybean 40 lbs P2O5 before corn Arns and Ruiz Diaz, 2012

17 Phosphorus Timing Considerations Annual P applications may be better than biennial applications with low soil test levels. Larger applications of P over removal rate can have significant residual value Builds soil test levels Can be performed when economics of larger applications are favorable Allows P to be omitted in times of unfavorable economic conditions

18 Considerations for P Placement Banding is expected to be superior when soil test levels are very low and only smaller rates of P are applied Broadcast applications would perform in the same way especially when there is good moisture in the surface (no-till?) Band and broadcast applications used together may be better than either one applied on its own

19 N and P on double crop soybean 50 Soybean yield (bu/acre) b 43 a Before wheat Before soybean Fertilizer application 120 lbs N + 60 lbs P2O5 Previous wheat yield=72 bu STP=17 ppm, STK=145

20 Potassium in soybean

21 Potassium in soybean Soil samples for K should be collected the same time of the year (significant season variability). Most of the K reminds in the biomass and can leach back to the soil. Plant uptake con be affected by poor soil aeration (compaction), cold or dry soils.

22 Soybean response to micronutrients Fertilizer treatments: Seven treatments: 5 individual nutrients, a mix, and a control. Broadcast, pre-plant. S= 15 lbs/acre Mn, Zn, Cu= 10 lbs/acre B= 5 lbs/acre Mix Intensive soil and tissue analysis. Uppermost fully developed trifoliate at R3.

23 Soil test with fertilizer application B a 5 4 Zn a Soil test B (ppm) b Soil test Zn (ppm) 3 2 b Pre-fertilizer Post-harvest 0 Pre-fertilizer Post-harvest Soil sampling Soil sampling Mn a Soil test Mn (ppm) b 10 0 Pre-fertilizer Soil sampling Post-harvest

24 Soil test with fertilizer application S Cu Soil test S (ppm) Soil test Cu (ppm) Pre-fertilizer Post-harvest 0.0 Pre-fertilizer Post-harvest Soil sampling Soil sampling

25 Change in tissue nutrient concentration S Zn Mean = 0.006% p = Mean = 6.620ppm p = Mn Tissue S (%) Cu Tissue Zn (ppm) Mean = 4.762ppm p = Mean = ppm p < Tissue Mn (ppm) Tissue Cu (ppm)

26 Plant sampling and analysis Any plant stress (drought, heat, soil compaction etc) can have a serious impact on nutrient uptake and tissue nutrient concentrations. A low value in the plant doesn t always mean the nutrient is low in the soil and the plant will respond to fertilizer. Tissue data interpretation can be more challenging for some nutrients ongoing research.

27 Plant sampling and analysis Iron uptake and soybean variety 1000 Soybean Tissue Fe (ppm) NT Var. Tolerant Var. Soybean variety

28 Soybean yield response across Soybean yield (bu/acre) locations NS Mix-Zn= 3.5 bu/acre 0 Mix B Control Mn S Cu Zn Treatment

29 Starter and foliar application of micronutrients for soybean Nutrient application rates, 6 locations for soybean N P2O5 K2O Fe Mn Zn Cu B Starter lbs/acre Foliar NPK NPK + micros NPK NPK + micros Cu, Mn, and Zn as EDTA Fe as HEDTA

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31 Soybean yield - starter Yield (bu/acre) b a a 40 0 None NPK NPK + M Starter Treatment p=0.082 Across locations

32 Soybean yield - foliar Yield (bu/acre) None NPK NPK + M Starter Treatment p=0.901 Across locations

33 Field variability soil Zn Zn 0.8 Zn (ppm) Distance (feet) Zn (DTPA), 2012

34 Micronutrients soil test Zn Mn OM ph ~1500 ft

35 Soybean Fe with the seed Seed-applied Fe No Fe fertilizer Chelated Fe fertilizer: EDDHA Fe (6.0%) 0.3 lbs Fe /acre

36 Soybean yield with seed-applied and foliar Fe fertilizer 40 Yield (bu/acre) ED 6% HE 4.5% No foliar c c c a ab ab c c c b a ab No-SC W-SC No-SC W-SC Susceptible Var Tolerant Var Treatments Ruiz Diaz, 2010

37 Soybean yield with seed-applied Fe fertilizer a c a b Grain yield (bu/acre) Susceptible Var. Tolerant Var. Seed-appled Fe No Fe fertilizer

38 Low ph can be a significant problem for soybeans in Kansas ph 5.6 ph 4.2 Mengel, 2009

39 Typical target ph in Kansas Legumes usually show more response than corn to lime. For most cropping situations (including soybean) in eastern KS, the target ph is 6.0, with lime recommended at ph<5.8.

40 Summary Fertility requirements are best determined by soil testing and other considerations such as crop removal and experience. Soybeans can respond to P placement under low soil test P. Soybeans are very sensitive to seed placed fertilizer. Nutrient removal is much higher than other crops per bushel.

41 Summary Response to S and micros are usually small and affected by soil conditions (texture and OM). Monitor soil test K, and solve soil compaction, and planting issues. Optimum soil ph is a key factor for soybean, lime rec if ph < 5.8.

42 Questions? Dorivar Ruiz Diaz