DIPARTIMENTO DI SCIENZE AGRARIE E AMBIENTALI PRODUZIONE, TERRITORIO, AGROENERGIA Conservation agriculture: productivity and carbon storage in soil Marco Acutis - University of Milano - DiSAA.
The agro-ecosystem Climate radiation temperature rain Driving variables Atmosphere Composition Pollution Economical and social variables ESTERNALITY OM (products) (fluxes of money) CO 2 NH 3 (volatilization) livestock storage treatments distribution Land and farm organization Biologic environment weeds Soil microbiology diseases pest Plant genotype productivity Genotype-environment interaction Crop management Tillage (or no tillage) Irrigation fertilization weeding Pest management Soil Chemical and physical properties water Dynamics of nutrients temperature CH 4 NO 3 (leaching and runoff) NO x N 2 O Pesticides (in leaching, runoff and atmosphere) Erosion (runoff) P (erosion and runoff) Landscape
Conservation agriculture in the World Total: 116,9 millions ha Canada 13,5 USA 26,5 Europe 1,2 Rest of the World 3,8 China 1,3 Brazil 25,5 Paraguay 2,4 Argentina 25,8 Australia 17.0 (Derpsch, R. and Friedrich, T., 2010)
Introduction In the last 30 years agriculture was characterized by: Intensive usage of the soil, Simplification in cropping systems, Reduction of yield increments Increase of the cost to produce yield, In this context tillage is a critical point
Critical aspect of tillage High energy required; Organic matter mineralization; Risk of erosion; Deterioration of soil structure; More evaporation from soil. Reconsider the role of soil tillage
Conservative agriculture Main characteristics Minimal soil disturbance, no soil layers inversion (sod seeding or minimum tillage) Permanent soil cover (crop residuals and cover crops) Crop rotation, against pest, diseases and weeds
Objectives of CA Main objectives are: Increase of soil s OM content, mainly in surface layers Reduction of erosion; Reduction of soil compaction; Increase of soil biomass and biodiversity; More efficiency of irrigation and fertilizers; Reduction of costs.
Increase of SOM. Crop residuals and no tillage (or reduced tillage) allows for Low OM mineralization rate Improvement of soil structure stability Better crop utrition Increase of microbial biomass and biodiversity Efficient water use (better hydrological characteristics) Reduction of CO 2 emissions
% S.O. OM trends (example) OM content (after 7 years for SS, and after 10 for MT) 2,25 2,00 1,75 1,50 +63% +52% 1,25 1,00 0,75 0,50 0,25 +2 +1% 0,00 0-20 cm 20-40 cm 0-20 cm 20-40 cm 0-20 cm 20-40 cm SS MT conventional Arato source: DiSAA experiments
Erosion control Erosion is at world level one of the main sources of loss of productivity (and water eutrophication). Erosion: from 0 to 200 t ha -1 of soil losses Erosion do not happens only in hillslopes, but also with a 1% soil slope Averaged results from some experiments: tillage Soil losses (t ha -1 ) Conventional 29.4 Sod seediing 3.8
Difficulties in implementing CA Yield reduction respect to conventional, mainly in the first years Risk of increase of chemical use for crop protection and weeds; Needs of special machinery; New technical knowledge needed for the new cropping systems. To avoid compaction there is the need of low-pressure pneumatics. (When there is compaction of soil it is difficult to go back in CA)
Precondition to apply CA Soil type machinery Weed management Irrigation management and hydraulic systems.
Precondition soil type CA is more difficult in: Silty soil: it is difficult to avoid compactation; Clay soil with Kaolinite. But is possible, due to an increase of organic matter CA is easy to implement in: Loam soils; Swelling (montmorillonite) Clay
Precondition Machinery Precision seeder for SS with localized fertilizer distribution Harrow for MT
Yield results
Po valley farms mais grain yield 15 14 t ha -1 13 12 11 10 9 8 7 6 2004 2005 2006 2007 2008 2009 2010 MT SS Aziende Conventional convenzionali Production-reduction 13% in MT and 23% in SS Fonte: sperimentazioni Di.Pro.Ve
Wheat yield Conventional Yield reduction 11% in SS; in MT there is an increase of 6% Source: interal
Example at regional scale Source: AgriCO2ltura project
Production cost reduction Reduction in tillage = reduction in costs After an initial conversion period there is a reduction of chemical fertilizer usage and somewhat a reduction of expanses for crop protection. There is to consider also that yield reduction could be very low
Fuel and Energy usage Tillage diesel Kg/ha energy MJ/ha Conventional Deep plowing 47 2191 Mechanical weeding 7 384 Harrowing (heavy) 33 1503 Sowing 6 269 TOTAL 93 4347 Minimum tillage Before sowing weeding 2 100 harrowing (light) 8 353 Sowing 7 351 TOTAL 17 804 Sod seeding Before sowing weeding 2 100 Sowing 9 480 TOTAL 11 580 (Della Marta Agricoltura Conservativa)
Convenience of CA Maize with subsidies Gross margin ha -1 Conventional Minimum tillage Sod seeding Maize price t -1
Margine lordo ( /ha) 1750 Maize no subsidies Gross margin ha -1 1500 1250 1000 750 500 250 0 Agricoltura Conventional Convenzionale Minimum tillage Semina Sod seeding su sodo -250-500 100 120 140 160 180 200 220 240 260 280 prezzo ( /t) Maize price t -1
NEW FRONTEERS IN CA SUBIRRIGATION Max irrigation efficiency (up to 90%) due to low evaporation, no runoff, reduced leaching; Incrase in yield: due to the possibility of late fertilization of maize; Soil surface is dry: reduction of weed development, and diseases, low use of chemicals Reduction of labor costs. Cost of plants: 4000 ha -1, life > 10 years Schema impiantistico (Fonte: Undedrip Srl)
NEW FRONTEERS IN CA SUBIRRIGATION CA-subirrigated Conventional Yield t/ha 12.8 11.8 Irrigation mm 170 352 N fertilization kg/ha 235 310 N uptake kg/ha 211 208 Percolation mm 37 215 N leaching kg/ha 9 73 CO 2 emission kg/ha 211 461
Conclusions CA is a valuable option: Increasing of soil fertility (ad SOC, but not everywhere) Reduction of not renevable energy sources usage Reduction of greenhouse gas emission ammonia and nitrate leaching Increase biodiversity but yiedls are in some case lower than in CA