Small Scale Hand hoe Conservation Farming a Tool for Biodiversity Conservation in Zambia

Transcription

1 Small Scale Hand hoe Conservation Farming a Tool for Biodiversity Conservation in Zambia Lydiah Gatere (1), Robert Delve (2), Peter Hobbs (1), Steve DeGloria (1), Johannes Lehmann (1) (1) Department of Crop and Soil Sciences, Cornell University, Ithaca, USA; (2) TSBF CIAT, Uganda

2 Biodiversity Conservation and Rural Livelihoods Improvement through Improved Technology COMACO Community Markets for Conservation a business model for rural development that links markets, agriculture and natural resource management in a way that addresses core needs of poor, food insecure families Found in the Game Management Area of the Luangwa National Parks Improving rural livelihoods around natural resource management a multi stakeholder program initiated and stewarded by Wildlife Conservation Society (WCS) Conservation Farming (Agriculture), one of the technology introduced in the Game Management Area for food security

3 Goal To investigate: (i) under which environmental conditions conservation farming works best; (ii) what types of organic amendments (qualities) are best for improving production potential under conservation farming; and (iii) how long it takes until conservation farming achieves its greatest yield potential under on farms conditions.

4 1. Environmental Variables Question 1: How well does conservation farming improve crop yields under a wide variety of environmental conditions? What are the reasons and how do these reasons depend on location? Objective. Establish the effects of (a) mean annual precipitation (MAP), (b) soil type (texture/soil particle distribution) and, (c) landscape position increases on crop yields through conservation farming. Determine the factors influencing yield improvement through conservation farming under varying environmental conditions.

5 Hypotheses: 1: Conservation farming increases crop yields the most under extreme adverse environmental conditions of low soil moisture and low N and P availability. 2: A threshold of MAP can be established below which conservation farming does not guarantee sufficient crop yields of 2 Mg/ha. 3: Increasing nutrient availability is more important than increasing water availability in conservation farming along wide environmental gradient. 4: Nitrogen is more limiting under low rainfall, whereas phosphorous is more limiting to crop yield under high rainfall.

6 2. Organic Amendments Question 2: Is organic matter stability or nutrient release more important for soil fertility improvement under conservation farming? Objective: Investigate the potential to improve nutrient availability by organic matter additions of contrasting quality in conservation farming along environmental gradients. Hypotheses : 6: Additions of stable organic matter such as bio char increases yields to a higher degree under high than low rainfall. 7: Additions of easily decomposable organic matter such as green manure increases yields to a higher degree under low than high rainfall.

7 Transect of the Three Agroecological Zones Chronosequence study Transect: COMACO and ASP region.

8 Design Variables: Mean annual Precipitation (MAP) 700 < X > 1200mm pa Landscape positioning Summit, mid slope and toe slope Soil Texture ie percentage clay Treatments (farms =540 as replicates): 1) no conservation farming as practiced and managed by farmers (control), 2) conservation farming as managed and practiced by farmers (control), Conservation farming supervised by researchers (researcher managed plots), 3) Gliricidia leaves 4) Manure 5) Biochar and fertilizer 6) Manure and fertilizer

9 Approach TT1 TT2 TT3 TT4 TT5 TT6 Conventional farmer practiced & managed CF Farmer practiced & Managed CF Researcher managed CF Researcher managed CF Researcher managed CF Researcher managed Gliricidia spp. leaves Manure Biochar & Fertilizer Manure & Fertilizer Three organic amendments (manure, gliricidia and bio char) are applied at 6 t C ha 1. Phosphorous and Potassium applied at 100 kg ha 1, Nitrogen applied at 200 kg ha 1, lime at 400 kg ha 1 and micronutrients. Input C:N Ratios Gliricidia leaves (dry 13 biomass) Cow Manure Bio char 850

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11 Analysis Soil samples (composites) from ~600 sites will be collected and analyzed for Physical properties (texture, bulk density) ie site characterization Chemical properties (ph, total C and N). Crop yields will be determined by sampling Cobs and stover separately, Cob and stover subsamples will be combined to give a weighted composite sample (according to the total yield of the respective plot), Tissue concentrations of nutrients and carbon isotope ratios will be quantified. The 13 C/ 12 C ratio of samples will be determined by isotope mass spectrometry. Stable carbon isotope composition will be expressed as δ13 C values (Farquhar et al., 1989) whereas δ13 C ( ) [(R sample/r standard) ]/1000.

12 Analysis SOC in relation to Organic matter and other nutrients hence yield variability Tissue N content will be quantified by dry combustion using a C N auto analyzer. Tissue concentration of P, Ca, Mg, K and micronutrients will be determined by set digestion using concentrated sulfuric acid in a heating block followed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP AES). (to allow differentiation between nutrient and water availability). (to be done at later date)

13 Grain Yield Results in Summit Landscape Yield in Different Soil Texture at Summit Position 6000 Maize Yields Kg/Ha Sand Loam Clay 0 Trad Trad PLUS CF Farm CF Gliric CF Manu CF BioChar Treatments CF Fert

14 Grain Yields Results in Mid Slope Yields in Different Soil Texture in Mid-Slope Position Yields Kg/Ha Trad CF Farm CF Glir CF Man CF Biochar Treatments CF Fert Sand Loam Clay

15 Grain Yield Results in Toe Slope Yield in Different Soil Texture in Toe-Slope Position Maize Yields Kg/Ha Trad CF Farm CF Gliric CF Manu Treatments CF Biochar CF Fert Sand Loam Clay

16 3. Chronosequence Question 3: How long does it take for conservation farming to improve crop yields? What are immediate benefits and what benefits require a build up of soil fertility over time? Objective: Assess the dynamics of soil fertility build up and crop yield under conservation farming over a 10 year establishment period. This is relation to a reference point of minimum tillage based on basins as the precise nutrient application for soil water management. Hypothesis: 8: Yield increases more by establishment of conservation farming than by soil fertility accrual over time. 9: The yield increase overtime after establishment of conservation farming is mostly due to improvement of nutrient and not water availability.

17 Materials and Methods Chronosequence of 10 years (Conservation Farming Unit CFU in Mumbwa) 10 farms at each conversion stages (1 year to 10 years in 2 year intervals). Each conversion interval, ten replicates sites were studied giving a total of 60 study sites. 10 fields were located each having conversion points of (0, 2, 4, 6, 8, 10) years with each block housing a control ie conventional field. Analysis: Soil samples at 0 15cm depth; within basin and between rows. Soils will be analyzed for: Total C and N, available nutrients using Mehlich 3 extraction followed by ICP analyses. (chapter in PhD thesis) P fractions (Univ. of Zambia Students) SOM content and distribution of C among SOM fractions; (Univ. of Zambia Students)

18 Acknowledgement SANREM CRSP (USAID) TSBF CIAT Dr. Robert Delve Zambia: COMACO/WCS Stakeholders (Lundazi and Mambwe) Agriculture Support Program SIDA (Mpika) Conservation Farming Unit (CFU Mumbwa) World Agro forestry (ICRAF) Msekera Research Station University of Zambia Cornell University Mario Einaudi Summer Travel Grant Richard Bradfield Award Presbyterian Church Ithaca Drs. Johannes Lehmann, Peter Hobbs, Stephen DeGloria.