Building healthy soils for healthy crops LORI HOAGLAND ASSISTANT PROFESSOR PURDUE UNIVERSITY

Transcription

1 Building healthy soils for healthy crops LORI HOAGLAND ASSISTANT PROFESSOR PURDUE UNIVERSITY

2 Outline v What is soil health and why is organic ma7er so important? v How do management prac:ces influence soil health and what are the implica:ons for vegetable crop produc:vity? v How can you determine how your management prac:ces are influencing soil health on your farm?

3 What is soil health? Organic Ma*er Aggregate Stability Organic Ma*er Soil Strength Available Water Chemical Organic Ma*er ph Nutrients Organic Ma*er Disease Suppression Drought tolerance (Charlie White, PSU)

4 Soil organic mader v Key component of soil health - glues soil aggregates together - contributes to soil CEC - absorbs and holds soil water - source of plant nutrients - energy and food for soil organisms v Formed over millennia from plant, animal and microbial residues v Must be con:nually renewed to maintain soil health

5 Change in SOM with culhvahon (Brady and Weil, 2002) SOM is made up of different pools with variable rates of decomposi9on

6 HOW DO MANAGEMENT PRACTICES INFLUENCE SOIL HEALTH AND WHAT ARE THE IMPLICATION FOR VEGETABLE CROP PRODUCTIVITY?

7 Specialty crop systems trial ( ) Intensive conven1onal system - Inorganic fer:lizers Intensive organic system - Winter cover crop - Compost fer:lizer Soil- building organic system - Winter cover crop - Compost fer:lizer - Cash crop alternates with summer cover crop - Soil health declined - Soil health improved slowly - Soil health improved rapidly v Crop rota:on: popcorn, soybean, tomato, and carrot v Few differences in yield v What if we introduce stress?

8 How does crop systems management influence mycorrhizal communihes and drought tolerance? Lisseth Zubieta v Arbuscular mycorrhizal fungi

9 How does crop systems management influence mycorrhizal communihes and drought tolerance? v In the absence of water stress, AMF improved water status and increased soybean growth regardless of source v In the presence of water stress, plants grown with AMF from the organic system had greater drought tolerance and yield

10 High tunnel soil management project ( ) v Intensively managed (heavy food traffic, mul:ple crops/growing season, high nutrient needs) v Limited crop rota:on v High evapotranspira:on/limi:ng leaching events Ma* Rudisill Pepper Treatments: Control (no amendment), Urea, Chicken Manure, Green Manure (vetch/alfalfa)

11 ImplicaHons for soil health v Soil quality declines in urea and control treatments in high tunnel v Green manure treatment improves soil health in both systems v Soil EC higher in high tunnel regardless of treatment v Pepper yield greater in high tunnel/not affected by amendment v What if we introduce crop stress?

12 Bioassays with snap bean and Rhizoctonia solani v Drama:c reduc:on in health of plants grown in high tunnel rela:ve to open field v Green manure mi:gates nega:ve impact of high tunnel v Nega:ve effects eliminated with soil steriliza:on - > biologically mediated OF a a a B a CNT UR GM CM CNT UR GM CM Dry Shoot b HT b a A b OF B HT A a a a a a b b b CNT UR GM CM CNT UR GM CM Dry Root

13 Soil biocontrol project ( ) v Phytophthora blight v Biological control: control of pathogen with beneficial microorganisms v Biocontrol op:ons - cover crops (brassica, cereal rye, wheat) - vermicompost - biochar v Greenhouse trials with infected soil h7p:// journal/v3/n4/full/nrmicro1129.html

14 Soil biocontrol project results v Biochar and wheat cover crops altered soil microbial community composi:on and reduce root infec:on by P. capsici v Biochar amendment and wheat cover crops improved pepper produc:vity Penewawa Soil B * * * * Soil B (high OM) * * * * * * * * * * * * * * * 0 Change in soil microbial community Root weight Shoot weight

15 How can you build soil health and increase resilience on your farm? v Plant cover crops v Apply organic amendments v Reduce soil :llage v Rotate crop families v Provide con:nuous plant cover Plant rhizosphere (E. Brennan) h7ps://microbewiki.kenyon.edu/index.php/plant_growth_promo:ng_bacteria

16 HOW CAN YOU DETERMINE HOW MANAGEMENT PRACTICES ARE INFLUENCING SOIL HEALTH ON YOUR FARM?

17 Standard soil test v Es:mates nutrients available for plant uptake v Total soil organic ma*er, soil ph, and Ca1on Exchange Capacity (CEC) v Advantage: - rela:vely inexpensive v Limita:on: - no or very limited informa:on on biological or physical proper:es

18 Soil health test v Standard nutrient analysis plus physical and biological indicators v Advantage: - informa:on on soil chemical, physical and biological status of soil - many provide management recommenda:ons for iden:fied constraints v Limita:on: - Cost: $50- $240 - Some need access to equipment on the farm like a penetrometer - Interpreta:on of results are a bit fuzzy indicators (not absolute) Valuable for tracking changes over 9me

19 Soil health indicators v Soil texture: propor:on of sand, silt and clay - func:on of soil parent material - virtually unchangeable except for erosion important for soil test interpreta9on

20 Soil health indicators v Aggregate stability - ability of soil aggregates to resist erosion, slaking, crus:ng healthy soils s9ck together

21 Soil health indicators v Surface and subsurface hardness - measure of penetra:on resistance - important for water infiltra:on and crop roo:ng

22 Soil health indicators v Ac1ve soil carbon - organic ma7er that is readily available for microbial use - simple compounds that have not been stabilized by associa:on with mineral par:cles Mineral Associated Organic Ma7er Ac:ve Carbon Mineral Par:cle Figure Source: M. Kleber et al. Biogeochemistry (2007) 85:9-24.

23 Soil health indicators v Microbial ac1vity and community composi1on - What types of microbes are present? - How ac:ve are they? - Important for nutrient mineraliza:on and availability for crop uptake - Important for media:ng bio:c and abio:c stress

24 Soil health indicators v Poten1ally mineralizable nitrogen - Nitrogen expected to be released from organic ma7er by soil microbes - Func:on of ac:ve organic ma7er pool and soil microbial ac:vity

25 Soil health indicators v Pathogen pressure - pathogen counts (direct) - bean root assay (indirect)

26 Soil health indicators v Salinity: soluble salt content of the soil - electrical conduc:vity (EC) - affects soil :lth and crop produc:vity

27 Soil health indicators v Heavy metal screening - recommended for urban areas

28 RecommendaHons Cornell Soil Health Test v Value provided for each physical, biological and chemical indicator v Color coded ra:ng/score for each indicator v Overall score provided v Site- specific constraints iden:fied v Specific management prac:ces suggested to address constraints h7p://soilhealth.cals.cornell.edu/extension/test.htm

29 Management recommendahons Cornell Soil Health Test - Biological concerns linked to NRCS prac1ce codes Short term Long term NRCS Code h7p://soilhealth.cals.cornell.edu/extension/pdfs/nh_nrcs_soilhealthmanagementop:onstable.pdf

30 Summary v Soil health is important for maintaining crop produc:vity and environmental health v Soil organic ma7er must be con:nually replenished to build and maintain soil health v Management prac:ces can alter soil health and impact crop produc:vity par*cularly under stress v Many for tracking changes in soil health using soil chemical, physical and biological indicators

31 QuesHons???