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RESIDUE EFFECT ON WATER MOVEMENT

Notes from the 2003 Annual Meetings American Society of Agronomy Crop Science Society of America Soil Science Society of America Bobby Brock October 2004.

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RESIDUE EFFECT ON WATER MOVEMENT

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  1. Notes from the 2003 Annual MeetingsAmerican Society of AgronomyCrop Science Society of AmericaSoil Science Society of AmericaBobby BrockOctober 2004

  2. Crop Residue Symposium - J. L. Hatfield-in dry springs, residue may increase soil water by 1-2 inches-nutrient efficiency is directly linked to moisture-need to see yield as series of events-yield variability year to year decreases a lot with surface residue-need more residue on surface, where it can increase infiltration-crop varieties respond differently After only one season of conventional cultivation, having been in fescue for 11 years, a lack of surface cover results in crusting. RESIDUE EFFECT ON WATER MOVEMENT Residue increases lead to infiltration increases.

  3. Dr. Pikel- management change does not always result in more OM -loamy sand needs 7-9 years to get improved OM-silt needs 5-7 years to get improved OM-clay needs 3-5 years to get improved OM-when OM reaches low level, more fertilizer does not help-plant reside is about 40 percent carbon-Childs (national corn yield champion) uses 44,000 seed/ac and has returned 10 tons/ac/yr corn stover since 1990-root growth gives more OM from exudates and small root turnover Big flower vetch as a winter cover also helps to increase SOM.

  4. Robust cotton and peanut plants no-tilled into bahia sod. Aside from some N-fixing, bahia is known to support high levels of friendly fungi. Rice Talk-microbes are gate keepers-more fungi equal more OM-aggregation strongly affected by VAM-adding manure does not increase macro aggregates with tillage-build up of C and organisms release N-more NO3 in soil with tilled system (6 year study) -high microbe population gives less pathogens -tillage increases N mineralization rate Organic matter holds lots of nitrogen. Amounts released may lead to reduced inputs of fertilizer N.

  5. Transgenic Corn Effect on Soil Microbes – Cornell University-no significant difference on microbe and arthropod population-no significant difference on nitrification-no significant difference on respiration-same results re: corn earworm insecticideGreen Manure -standard is fumigate to control pathogen-increase SOM to reduce problem (by release of chemicals by decaying OM)-assume amount of biomass more important than type of biomass-incorporate and incubate GM for 9 months-GM did suppress disease

  6. Kansas State study on a silt loam shows-that NT significantly increased soil macro aggregate and conservation of C and N inputs -physical protection of OM by NT explains C&N conservation resulting from NT Good aggregation is evident where no-till and residue added are continued.

  7. Paustian Conservation agriculture needs to: -improve and maintain soil OM, fertility -increase plant diversity-efficient use of inputs-more use of biological N supply-multiple-use products -reduce fossil fuel uses-soil nutrients: emphasize mineralizable NPS, CEC, and buffer capacity -wheat bean not increase C-include corn and increase vetch to get good increase in top meter Austrian winter peas can provide diversity and supply N. Will Mann, Halifax. Some brassicas also extend tap roots to relieve soil density, as well as provide diversity

  8. In Brazil, NT gives-30% more yield in a dry year-three-fold increase in net profitRegulating Soil N Mineralization-tillage and placement only way now (also inhibitors) -may use transgenic crops in future to time the mineralization to coincide with plant needs (gettin’ fancy!)Cattle Grazing-grazed plant has more root exudation-soil microbes cycle N-previous findings: less N mineralization with intensive grazing, but FL study shows:-more microbes with intensive grazing-more carbon with intensive grazing

  9. N Mineralization-OM may give 30 to 100 % of crop nitrogen needs-N mineralization significantly more in forest than old field Sunn hemp provides large amounts of biomass and nitrogen Winter cover of hairy vetch

  10. Impacts of Soil Amino Acids on Corn-Soybean Yields-soil N 95-98% of total N is organic N, about 20-35% of that is insoluble acids-plant N is almost all amino acids-soil N about 60% amino acids and about 20% amino sugars-amino acids very important in crop yields-conservation tillage gives significant increase in SOM, N, and biological biomass --SOC increases 23% --N increases by 39%-as amount of carbon goes up bulk density goes down-about 35% of carbon applied remains in soil

  11. In Georgia Piedmont Soils-old micro aggregates remain plus develop new ones with no-till-amino sugars derived from fungi and bacteria will be more in NT than CT-NT had about 1/3 more with most macro aggregates and micro aggregates within the macro aggregates in the top 2 inchesR. Follett-corn planted into brome which was 13 years old; no response to N rates-amount of carbon not changed much over 4 years, but larger aggregates decreasedSweet Corn Root Rot-complex of pathogens cause it-added organic amendments to soil; manure tilled in; there was disease suppression, but this effect was lost in six months

  12. Need QUALITY of POM, not just amount Mixture of grass/legume for winter cover helps give quality and amount of biomass

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