Lori Hoagland Associate Professor and Soil Microbial Ecologist Department of Horticulture and Landscape Architecture Purdue University . History in ag. . Different types . Factors affecting efficacy . Research trial . Considerations for use . Humus theory: need regular additions of organic matter to the soil to maintain fertility and crop yield  . Focus shifted in the 1800’s - Carl Sprengel (1787-1859), Sir Humphrey Davy (1778-1829), and Justus von Liebig (1803-1873) refuted humus theory and shifted focus to individual chemical elements . Haber-Bosch process (early 1900’s) - inorganic nitrogen fertilizer Aristotle (384-322 BCE) . Sir Albert Howard (1873 – 1947) “the father of organic farming” - learned about importance of organic matter studying composting in India - “the health of the soil, plant, animal and man is one and indivisible” . Rudolf Steiner (1861-1925) . Lord Northbourne (1896-1982) . Lady Eve Balfour (1898-1990)

. Jerome Irving Rodale (1898-1971) (Brady and Weil, 2002) . Masanobu Fukuoka (1913-2008) Loss of soil organic matter over time No legal definitions for the term ‘biofertiliser’ in US

. Substance containing living microorganisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant (Vessey, 2003) . Replace soil nutrients (i.e. by biological N2 fixation) . Make nutrients more available to plants (i.e. by solubilization of nutrients)

. Increase plant access to nutrients (i.e. by increasing the volume of soil accessed by the root system) (Vacheron et al., 2013) . Soil bacteria that fix atmostphere nitrogen once established inside plant roots or stems . Discovered in 1888

58 million years ago Martinus Beijerinck Inoculants . Symbiotic association of the mycelium of a fungus, with roots of certain plants in which the hyphae form a closely woven mass around the rootlets or penetrate the cells of the root . Fungus root - >90% of all land plants - Wide host range and cosmopolitan distribution worldwide 400 million years ago . Root-colonizing bacteria that form symbiotic relationships with many plants . Rhizobacteria with PGP-activity include strains belonging to genera Bacillus, Pseudomonas, Azospirillum, Azotobacter, Alcaligens, Arthobacter, Agrobacterium, Burkholderia, Comamonas, Pantoea, Rhizobium

(Farag et al., 2013) Crop Cultivar Growth stage

Microbial strain/s Climate conditions Propagule concentration Soil type Formulation Cultural practices Microbial inoculum Environment • Azospirrilum brasilience • 20 historic and modern wheat varieties • Field (2 locations) and greenhouse trials • Treated & untreated controls • Replicated and randomized trials 2006-2009 . Initial results at field site A in year one were impressive -> (10-20% yield and protein gains) . Yield protein benefits varied by location

Average Organic Inorganic Rainfall Matter N Location inches (%) (lbs/ac) A 9.8 2.37 18.6 <- greater benefits B 20.4 3.49 28.7

. Benefits varied by year Inoculated Uninoculated (Hoagland et al., 2008) . Benefits varied by wheat variety

20 18 * * * 16 * 14 * 12 10 8 6 4 2

Increase in yield (bu/ac) yield in Increase 0

Alba Fultz Eltan Finch Hood Alicel Finley Xerpha Hatton Thome DelmarTurkey Madsen MasamiGoldcoin Florence WA7976 Buchanan GoldenCr Bauermeister Cultivar . In some cases, the inoculant had severe negative effects Inoculated Uninoculated (Hoagland et al., 2008) . Compared 10 commercially available AMF inoculants and lab grown AMF cultures on corn, sorghum, trident maple and sweetbay magnolia

. Results: - most commercial inoculants failed to promote root colonization - some inoculants increased plant growth, but more likely due to non-mycorrhizal ingredients in the products (fertilizers, PGR’s)

My lab’s experience with commercial AMF inoculants . Null Synergism between arbuscular mycorrhizal fungi and nitrogen . Positive fixation bacteria (Schütz et al., 2018) . Negative Mycorrhiza “helper” bacteria (Bonfante and Anca, 2009)

Mycoparassitism of arbuscular mycorrhizal fungi by the fungus Trichoderma harzianum (De Jaeger et al., 2010) . Potential opportunity to help supplement fertility needs, particularly in dry environments and soils with low organic matter and high total soil P (Schütz et al., 2018)

. Potential opportunity in greenhouse and vegetable transplants

. Purchase products from reputable companies with independent, replicated research trials

. Purchase fresh inoculants and store them properly . Definitions . Different types . Potential mechanisms of action . Research trials (tomato/pepper) . Considerations for use . First commercial seaweed extracts manufactured 60 years ago (Craigie et al., 2011)

Schematic representation of effect and mechanisms(s) of activity of seaweed extracts (Sangha et al., 2014) Definition in the European Union “A material that, when applied to a plant, seed, soil or growing media - in conjunction with established fertilization plans, enhances the plant's nutrient use efficiency, or provides other direct or indirect benefits to plant development or stress response.” Do not contain nutrients

Definition in the United States “Products derived from natural or biological sources..” . Organic plant biostimulants - Humic substances - Protein hydrolysates - Seaweed and other plant extracts

. Inorganic plant biostimulants - Silicon . A mixture of complex organic compounds having yellow to black color formed by transformations (humification) of organic residues of plants and animals by soil microorganisms

Humins: not soluble in water at any pH value Humic acids: not soluble in water under acidic conditions (pH < 2) Fulvic acids: soluble in water under all pH conditions . A mixture of organic/inorganic compounds from seaweed biomass using different manufacturing systems such as alkaline or acid hydrolysis or cellular disruption under pressure or fermentation

Ascophyllum nodosum

Fucus sp. Carbohydrates Minerals Laminaria digitata Phenolics Amino acids Vitamins Phytohormones

Ecklonia maxima . Mixtures of polypeptides, oligopeptides and amino acids that are manufactured from protein sources

Leather wastes using partial chemical and/or enzymatic hydrolysis

Fish wastes

Feather wastes

Carbohydrates Phenolics Plant biomass Minerals • Increase germination • Improve nutrient uptake • Improve nutrient-use efficiency • Increase tolerance to and recovery from abiotic stresses (salt, water, heat, heavy metals) Genetically determine biomass partitioning

Nutrients, Water Yield and quality Sunlight

Plant stresses Yield loss due to stress Cold • Nutrients, Water Yield loss • Waterlogging Sunlight Yield and quality • Drought • Salt Heavy metals • Yield loss due to stress • Heat Yield loss • Pathogens Nutrients, Water Sunlight Yield and quality • Insect pests

(Brown and Saa, 2015 FIPS) Agricultural biologicals • Trichoderma species -> two product formulations and untreated control • Two tomato varieties • Field trial • Replicated and randomized trials 2011 Increased tomato transplant Increased transplant survival size in the greenhouse and RS+WP1 increased biomass

* * *

* indicates significant difference from the control • Trichoderma virens and protein hydrolysate, alone and in combination • Untreated control • Infected soil • Greenhouse trial • Replicated and randomized trials 2017 0.8 Combo had greater root biomass a 0.7 and health when subject to P. capsici stress b 0.6 b b 0.5 0.4

g root 0.3 0.2 0.1 0 control SeedSeed Phdrencg SeedSeet trt, trt. Control treatment PHdrench + drench Pepper root biomass (P<0.05) . Potential opportunity to help plants acquire nutrients in low-quality or degraded soils . Potential opportunity to help plants tolerate abiotic and biotic stress . Purchase products from reputable companies with independent, replicated research trials . What are your experiences using biofertilizer and Questions? biostimulant products? . Bonfante, P., Anca, I.A., 2009. Plants, mycorrhizal fungi, and bacteria: a network of interactions. Annual Reviews of Microbiology 63:363-83. . Craigie, J.S., 2010. Seaweed extract stimuli in plant science and agriculture. Journal of Applied Phycology 23(3): 371-393. . De Jaeger, N., Declerck, S., and de la Providencia I.E., 2010. Mycoparasitism of arbuscular mycorrhizal fungi: a pathway for the entry of saprotrophic fungi into roots. FEMS Microbial Ecology 73(2):312-22. . Hoagland, L., Murphy, K., Carpenter-Boggs, L., Jones, S., 2008. Improving nutrient uptake in wheat through cultivar specific interaction with Azospirillum. Second ScientificConference of the International Society for Organic Agricultural Research (ISOFAR), Modena, Italy. pp. 526-565 . Schutz, L., Gatttinger, A., Meier, M., Muller, A., Bolter, T., Mader, P, Mathimaran, N., (2018). Improving crop yield and nutrient use efficiency via biofertilization – A global meta-analysis. Frontiers in Plant Science 2204 . Vessey, 2003. Plant growth promoting rhizobacteria as fertilizers. Plant and Soil 255(2): 571-586.