Soil biology and system management

Transcription

1 1 Soil biology and system management Lisa M. Fultz Assistant Professor Soil Microbiology of Cropping Systems LSU AgCenter Baton Rouge, LA Award #:

2 2 Ecosystem Functions from the Soil Perspective Physical Soil texture, compaction, PAW, aggregate stability Chemical ph, SOM, CEC, nutrients Biological Microbial biomass and activity, SOC, nutrient cycling, diseases

3 To Understand Soil Health We Must Understand Soil Biology 3 Plant growth enhancement Aggregate formation Water flow Nutrient cycling Water storage N fixation Plant protection Soil Biota Decompose residues Water filtration Pathogen supression Photo credit: Lisa M Fultz, LSU AgCenter Slide design: Jennifer Moore-Kucera, NRCS-SHD Detoxify pollutants Influence atmosphere composition

4 Soil Health Identifies the Importance of Soil Biology To Enhance Ecosystem Services 4 Increase amount, types and availability of plant residues. Minimize disturbance Increase #s and types of soil organisms Aggregate Stability OM Transformations Humus Formation Plant Growth, Productivity Resist erosion Increase H 2 O infiltration and storage Enhance water/air quality C sequestration Climate mitigation Biogeochemical Cycling Release plant available nutrients

5 5 Ecological Challenges to Soil Resilience Abiotic Variables: Depleted water sources Changes in precipitation patterns Extreme weather Erodibility indexes (>200 tons ha -1 y -1 ) Cultural Practices: High disturbance agronomic systems Intensive/ frequent tillage Low diversity Fallow periods Low residue return

6 6 Management Practices to Enhance Soil Health and Combat Soil Degradation Increase plant residues returned to the soil Perennial grasslands/forage lands Use crop rotations or cover crops Integrate cattle into cropping system Convert to conservation or no-till Enroll in conservation management programs

7 7 Integrated Crop-Livestock Agroecosystems Great flexibility Divide fields to suit needs/skill/resources Cotton Monocultures Grass-cattle Grain - Cotton Pullman clay loam soils ph = 7.4 SOM = % 34% clay

8 Fultz, L.M., Moore-Kucera, J., Zobeck, T.M., Acosta-Martinez, V, & Allen, V.G. (2013) 77: CTN_1 ICL_1 CTN_2 CTN_3 ICL_2 ICL_3 ICL_4 System 0 Soil organic C (g kg -1 ) Grassland 31% increase in SOC following 13 years under ICL management 8 Deficit irrigated continuous cotton Deficit irrigated bluestem & crop rotation Deficit irrigated continuous cotton Deficit irrigated continuous cotton Dryland forages & cotton Deficit irrigated perennial grasses Bluestem and fully irrigated row crops

9 9 Water use and productivity -Allen et al Agronomy Journal Integrated system compared to continuous cotton Per hectare 25% less irrigation 36% less N fertilizer Decreased chemical inputs (pesticides and plant growth regulators) Avg. over 10 years profitability was similar when comparing the two systems

10 CTN_1 ICL_1 CTN_2 CTN_3 ICL_2 ICL_3 ICL_4 System 0 Soil organic C (g kg -1 ) Grassland Deficit irrigated continuous cotton Deficit irrigated bluestem & crop rotation Deficit irrigated continuous cotton Deficit irrigated continuous cotton Dryland forages & cotton Deficit irrigated perennial grasses Bluestem and fully irrigated row crops ICL s increased aggregate stability 2-3x s that in continuous cotton 10

11 SOM and Aggregate Stability Mean weight diameter (mm) Annual crops 11 Perennial Mean weight diameter (mm) Relationship between increasing SOM and MWD (proxy for stability) Critical SOM value for enhanced aggregate stability Annual crops y = 0.04e 0.09x r² = 0.73*** Perennials Soil organic matter (g kg -1 )

12 12 Mean weight diameter (mm) cm Y= 0.05x r ² r = p < cm Y= 0.02x r ² r = p < Relative abundance of arbuscular mycorrhizal fungi (mol%)

13 13 What are the ecological impacts of increased fungal richness? Fungal operational taxonomic units (proportional to system area) Converting part or all of the field to rotation or perennial-based agroecosystems Increased Fungal Richness Increased SOM Fungal richness Diversity (diversity) Monoculture Cotton CTN_1 CTN_2 Rotations/ Perennial Systems FRG_CTN OWB_BER FRG_RC Monoculture Cotton Fungal richness (diversity) Rotations/ Perennial Systems Davinic, M. 2014, Ph.D. Dissertation

14 14 Available Soil P (ppm; Mehlich3) Do these shifts in microbial groups influence nutrient cycling? Fungal Class Onygenales y = x R² = Microbial composition influences the release of plant-available nutrients Bacterial Phylum Acidobacteria y = x R² = Relative abundance (%) Onygenales or Acidobacteria

15 15 Field Design Split plot design: Cover crop (CC) as main plot and N rates as sub plots 32 treatments: 8 cover crops and 4 N rates, with 4 reps for each CC*N treatment within a cover crop main plot N rates: 0, 235, 268, 302 kg Urea ha -1 Cereal radish + rye mix Radish (Raphanus sativus var. longipinnatus) Fallow Hairy vetch (Vicia villosa Roth) Crimson clover (Trifolium incarnatum L) Cereal rye (Secale cereale) Winter pea (Pisium sativum L) Berseem clover (Trifolium alexandrinum)

16 16 Cover crop dry weight biomass 3000 [CELLRANGE] 2500 Biomass weight (g) [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] Fallow Berseem Clover Crimson Clover Hairy Vetch Winter Pea Cereal Rye Radish Rye+Radish

17 Soil organic matter 14.6% increase Fall 2014 to Fall [CELLRANGE] Soil Organic Matter (% LOI) [CELLRANGE] [CELLRANGE] [CELLRANGE] [CELLRANGE] 2.1 Fallow Legume Grass Brassica Rye/Radish

18 18 C cycling enzyme greater in spring, fallowing cover crops 90 B-glucosidase (mg p-nitrophenol g-1 hr-1) Fallow Legumes Grass Brassica Rye/Radish Fall 2014 Spring 2015 Fall 2015 Spring 2016

19 19 N cycling enzymes increasing over time 25 B-glucosaminidase (mg p-nitrophenol g-1 hr-1) Fallow Legumes Grass Brassica Rye/Radish Fall 2014 Spring 2015 Fall 2015 Spring 2016

20 Total microbial biomass increased with SOM Total Microbial Biomass (nmol g -1 ) y = x R² = Soil Organic Matter (% LOI) y = x R² = Nitrate-N (mg kg -1 ) y = x R² = Soil P (mg kg -1 ) Total Microbial Biomass (nmol g -1 ) Total Microbial Biomass (nmol g -1 )

21 Fallow Berseem Crimson Hairy vetch Winter pea Cereal rye Radish Rye+Radish 21 76% 85% 77% 85% 82% 81% 75% 74% Fallow Berseem clover Crimson clover Hairy vetch Winter pea Cereal rye Radish Rye+Radish 64% 93% 123% 70% 132% 128% 67% 69%

22 r 3 Corn yields increased following sses and legumes E BCD AB ABC A CD DE Corn grain yield (bu/a) F 40 20

23 nter annuals overseeded on a perennial ture 23 uthern Mississippi ef cattle operation inter annual mixture Oats Triticale Annual ryegrass Hairy vetch Red clover Crimson clover White clover Turnip Radish

24 al pasture ded with r annuals Total Microbial Biomass (nmol g -1 ) y = 57.9x R² = Soil Organic Matter (% LOI) y = x R² = y = x R² = Soil P (mg kg -1 )

25 25 F, P, and 3

26 26

27 27 Thank you! Lisa M. Fultz

28 28 arge macroaggregate roots Fibers

29 hat is the impact of ICLs on the ratio of ngi to bacteria (F:B)? Type of ratio impacts interpretation! Highest F:B (18:2/Bac) ratio in continuous cotton Marker common for saprophytic fungi No change between ICLs

30 30 hat is the impact of ICLs on the ratio of ngi to bacteria (F:B)? Type of ratio impacts interpretation! AMF/Bac ratio: cotton < rotation < perennialbased systems

31 tive: Evaluate short-term soil health changes g conversion of CRP back to cropland CRP Converted to annual crops ems (CRP vs. Converted CRP) hs (0-10, 10-30, 30-50cm) s (2012, 2013, 2014) histories: ages years enrolled erted CRP were enrolled and converted Semi-arid climate: Avg. annual temperature :16 C Avg. annual PPT : 475mm Soil: Amarillo fine sandy loam ph: 7.6 (0-30cm) SOM: 1.4% Sand: 71%

32 0cm Converted CRP change percent (%) Reference line is CRP Labile OM MBC Specific Metabolic Activities -C POM-N MBC α-galac/ MBC β-gluc/ MBC β-glm/ MBC qco

33 33 Gram Total bacteriagram + Actinomyc etes Total fungi Total bacteria Gram AMF Actinomycet es MF Fungi:Bact eria Gram + Total fungi Fungi:Bacter ia

34 34 ncreased soil organic matter ncreased total microbial biomass Perennial grasses over seeded w/winter annuals Annual corn w/cover crops y = 74.9x R² = 0.73

35 35