Soil physical properties in Brazilian soils under No-tillage systems

Transcription

1 UNIVERSIDADE ESTADUAL DE PONTA GROSSA SETOR DE CIÊNCIAS AGRÁRIAS E DE TECNOLOGIA DEPARTAMENTO DE CIÊNCIA DO SOLO E ENGENHARIA AGRÍCOLA Soil physical properties in Brazilian soils under No-tillage systems Neyde Fabíola Balarezo Giarola neydef@uepg.br

2 Goal To evaluate changing of some soil physical properties in Brazilian soils, under No-tillage system.

3 Contents Impacts of agriculture in Brazilian soils No-till: effects in soil physical properties Soil Bulk Density Tensile Strength Visual Soil Structure Quality Assessment Conclusions References

4 Impacts of agriculture in Brazilian soils MODERN AGRICULTURE: soil structure under higher stresses Plant demand f (grow?) Productivity Limits: f (soil structural condition)? Soil Structure STRESSES: traffic, M.O. losses, pesticides, crop succession,... - Structure degradation: short time - Structure recovering: medium-long time

5 Impacts of agriculture in soil physical properties FACTORS WITH INFLUENCE DIRECT INDIRECT Emergency and Plant growing WATER OXYGEN TEMPERATURE RESISTANCE Soil density Texture Structure Aggregation Porosity K( ), and others

6 No-till to modify soil physical properties? No-till makes changes in the soil in different rates and directions from that observed in soil management systems which include its mobilization. The degree which the No-till changes the soil properties is little known and very changeable, mainly due to the great variation of the soil and the climate where it is applied, and due to its great variation of operations, size of equipments, and kinds of crops used in the system, in the several regions and agricultural businesses.

7 No-till: effects in soil physical properties EFFECT ON BULK DENSITY : After 3 to 4 years, soil in No-till show up to the first 10 cm: BD Total Porosity ( Macroporosity ) - natural soil arrangement, when it is not revolved; - pressure caused by machinery traffic on clayey soil and by elevated level of humidity soils. (Vieira & Muzilli, 1984; Corrêa, 1985; Castro, 1989).

8 No-Till: effects in soil physical properties EFFECT ON BULK DENSITY: 0,90 0,95 1,00 1,05 1,10 1,15 1, Profundidade (cm) PC PM PD Soil Bulk Density under three soil tillage systems Ex. Latossolo Vermelho, clay: 700 g kg -1 (Derpsch et al., 1991)

9 No-Till: effects in soil physical properties EFFECT ON SOYBEAN PRODUCTIVITY: (Derpsch et al., 1991) Comparative productivity (%) PC PM PD Soil Preparation System Chemical fertility: upper in no-till (P, Ca, Mg,) Water: longer time availability in no-till Temperature: lower in no-till Bioporosity: bigger and continuous in no-till aeration in humid seasons, access to water in deeper layers. Alternative routes for root growing.

10 No-Till: effects in soil physical properties Corn Wheat Soybean Soybean Wheat Soybean

11 No-Till: effects in soil physical properties 11,0 10,0 9,0 PR = 0,078-4,138 R 2 = 0,76 Bd = 1,41 Mg m -3 No-Till Rot No-Till Suc Forest 8,0 Penetration Resistance (MPa) 7,0 6,0 5,0 4,0 3,0 2,0 PR = 0,0423-4,3368 R 2 = 0,71 Bd = 1,31 Mg m -3 PR = 0,0265-3,5357 R 2 = 0,72 Bd = 0,99 Mg m -3 1,0 0,0 0,3 0,4 0,5 Water content m 3 m -3

12 No-Till: effects in soil physical properties Tensile strength It is defined as the strength per area unit necessary to cause the soil fracture TS = 0,576 * (P/D 2 ) (Dexter & Kroesbergen (1985) Indicator of the soil structural condition

13 No-Till: effects in soil physical properties Tensile strength TS = 0,576 * (P/D 2 ) 0,576 = constant P = applied strength to promote rupture D 2 = effective diameter of aggregate Influenced by: Soil water content Clay content Organic matter content Chemical cements

14 No-Till: effects in soil physical properties Tensile Strength

15 No-Till: effects in soil physical properties Tensile Strength

16 No-Till: effects in soil physical properties Tensile Strength

17 No-Till: effects in soil physical properties Tensile Strength

18 No-Till: effects in soil physical properties Tensile Strength Cambissolo: Irati (PR) - franco argiloso 250 a a Tensil Strength (KPa) c *40,8 *34,5 *34,9 *38,3 b 50 0 Forest Conventional Tillage No-till 6 years No-till 9 years Tillage systems * Soil organic matter g kg -1

19 No-Till: effects in soil physical properties 220 Tensile Strength Frequência ,75 3,25 3,75 4,25 4,75 5,25 5,75 6,25 ln of tensile strength, (kpa) SDS SDR SDE

20 No-Till: effects in soil physical properties Soil Porosity FORESTRY ROTATION SUCCESSION 0-15 cm DEEP

21 No-Till: effects in soil physical properties Soil Porosity FOREST ROTATION SUCCESSION cm DEEP

22 How to assess soil physical quality? In the field: Assessing visual soil structure quality (revised Peerlkamp technique)

23 Why assess soil structure? Soil structure affects root penetration and water and nutrient availability for the crop Good, uniform soil structure helps ensure sustainable crop growth with minimum environmental problems

24 What is ideal soil structure? Ideal topsoil structure includes crumb and rounded, porous aggregates, weak enough to allow roots to grow and adsorb water and nutrients, strong enough to bear wheels and hooves This structure can also be vulnerable to compaction and erosion, especially if soil organic matter is low

25 Visual Soil Structure Assessment Spade test quick, cheap and gives a measure of field variability Developed as a mixture of the Peerlkamp scoring test (still in use), a Danish soil description method and a Scottish soil description/scoring method Developers of the method: Tom Batey (University of Aberdeen) Lars Munkholm (Århus University, Denmark) Bruce Ball (SAC)

26 Doing the test 1. Extract a spadeful of soil 2. Break up the spadeful 3. Assign a score between 1 and 5 compare with pictures in a key

27 Properties used in the assessment Ease of break up of the soil Size and appearance of aggregates Porosity Root appearance and location

28 Document extocument obtenu sur le site

29 Aggregates in Sq2, Sq3 and Sq4 Sq2 Sq3 Sq4

30 Sq1

31 Sq2

32 Sq3

33 Sq4

34 Sq5

35 Soil structure, soil strength and crop growth 3,5 3 Sq soil structure 2,5 2 1,5 1 0,5 0 Normal plough Min tillage Notillage Penetration resistance (Mpa) Relative vegetation index

36 Use of the scores Scores 1-3 are satisfactory Scores 3-5 need changes in tillage or cropping to sustain productivity e.g. loosen a compact zone Aim to reduce structural variability to increase crop consistency

37 Conclusions The assessment can tell you how good and uniform your structure is and whether you need to till to a different depth or control compaction more The main value is that it helps you to become aware of soil in a more rational way and become aware of how it responds to what you do to it

38 References BAYER, C.; MARTIN-NETO, L.; MIELNICZUK, J.; CERETA, C.A. Effect of no-till cropping systems on soil organic matter in a sandy clay loam Acrisol from southern Brazil monitored by electrón spin resonance and nuclear magnetic resonance. Soil Till. Res., 53:95-104, DERPSCH, R. Expansão mundial do plantio direto. R. Plantio Direto, 5:32-40, DREES, L.R.; WILDING, L.P.; SMECK, N.E.; SENKAYI, A.L. Silica in soils: quartz and disordered silica polymorphs. In: DIXON, J.B. & WEED, S.B., eds. Minerals in soil environments. Madison, Soil Science Society of America, p (Book Series, 1). EMBRAPA. Sistema Brasileiro de classificação de solos. 2ª. Ed. Rio de Janeiro: EMBRAPA Solos, p. LAL, R. Role of mulching techniques in tropical soil and water management. Ibadan, Nigeria, International Institute of Tropical Agriculture, p. (Technical Bulletin, 1). SHULZE, D.G. Na introduction to soil mineralogy. In: DIXON, J.B. & WEED, S.B., eds. Minerals in soil environments. Madison, Soil Science Society of America, p (Book Series, 1). SOANE, B.D.; OUWERKERK, C. van. Soil compaction problems in world agriculture.in: SOANE B.D. & OUWERKERK, C. van, ed. Soil compaction in crop production. Netherlands, Elsevier, 1994, pp USA. Department of Agriculture. Natural Resources Conservation Service. Soil Survey Staff. Keys to soil taxonomy. 8. ed. Washington, D.C., p. WAMBEKE, A. van. Soil of the tropics. New York, MacGraw Hill, p