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Managing maize-based cropping systems to increase soil carbon in northern Ghana J.B. Naab 1, J.W. Jones 2, J. Koo 2, and K.J. Boote 3 1 Savanna Agricultural.

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Presentation on theme: "Managing maize-based cropping systems to increase soil carbon in northern Ghana J.B. Naab 1, J.W. Jones 2, J. Koo 2, and K.J. Boote 3 1 Savanna Agricultural."— Presentation transcript:

1 Managing maize-based cropping systems to increase soil carbon in northern Ghana J.B. Naab 1, J.W. Jones 2, J. Koo 2, and K.J. Boote 3 1 Savanna Agricultural Research Institute, Wa, Ghana. 2 Department of Bio. & Agric. Eng., University of Florida, USA. 3 Agronomy Department, University of Florida, USA.

2 INTRODUCTION Among various ways to sequester CO2 from the atmosphere, increasing plant productivity is an option that could also lead to increased agricultural productivity and food security, especially in developing countries. Among various ways to sequester CO2 from the atmosphere, increasing plant productivity is an option that could also lead to increased agricultural productivity and food security, especially in developing countries. Agricultural production in northern Ghana is often constrained by low soil fertility especially N and P with resultant low biomass production Agricultural production in northern Ghana is often constrained by low soil fertility especially N and P with resultant low biomass production

3 Any increase in biomass also offers increased scope for carbon sequestration. Any increase in biomass also offers increased scope for carbon sequestration. Improvements in crop management leading to greater crop residue production may allow sufficient residues to be returned to fields. Improvements in crop management leading to greater crop residue production may allow sufficient residues to be returned to fields. Fertilization is a primary means for increasing plant production and crop yield. Fertilization is a primary means for increasing plant production and crop yield. Cereal-legume rotations complimented with the use of mineral fertilizers are options to improve soil fertility for sustainable crop production Cereal-legume rotations complimented with the use of mineral fertilizers are options to improve soil fertility for sustainable crop production

4 OBJECTIVES Conduct on-station and on-farm experiments to assess the potential of different cropping systems to sequester soil carbon Conduct on-station and on-farm experiments to assess the potential of different cropping systems to sequester soil carbon Collect minimum data set needed for adapting the DSSAT-CENTURY model for use in simulating the potential of various cropping systems to sequester soil carbon Collect minimum data set needed for adapting the DSSAT-CENTURY model for use in simulating the potential of various cropping systems to sequester soil carbon

5 Experiment 1 Cropping systems and fertilizer effects on maize productivity and soil carbon Treatments Treatments - Continuous maize + 30 kg N ha -1 - Continuous maize + 80 kg N ha -1 - Peanut – maize rotation + 40 kg N ha -1 - Mucuna – maize rotation + 40 kg N ha -1 - Bush fallow–maize rotation + 40 kg Nha -1

6 Measurements Soil carbon measurements in 2003, 2005, 2006 Soil carbon measurements in 2003, 2005, 2006 Biomass accumulation and partitioning Biomass accumulation and partitioning End of season total biomass End of season total biomass Grain yield Grain yield

7 Table 1: Effects of cropping system and fertilizer on residues returns to the soil each season Cropping systemN rate (kg ha -1 ) Crop residues returns (t ha -1 ) Continuous maize302.8a4.3a3.6a1.2a Continuous maize803.1a6.5b4.5ab2.1b Native bush-maize402.4ab*3.8a‡6.8bc* 2.3b 2.3b ‡ Mucuna-maize401.7bc†4.7a‡9.0c† 1.7abc 1.7abc ‡ Peanut-maize401.1c+4.8a‡8.7c 2.1bd 2.1bd ‡ LSD (0.05)

8 Effects of cropping system and fertilizer nitrogen on soil organic carbon Cropping systemN rate (kg ha -1 ) Soil organic carbon (%) Continuous maize300.43± ± ±0.02 Continuous maize800.43± ± ±0.11 Native bush-maize400.45± ± ±0.13 Mucuna-maize400.44± ± ±0.04 Peanut-maize400.45± ± ±0.02 LSD (0.05)

9 Effects of cropping system and fertilizer nitrogen on maize grain yield Cropping systemN rate (kg ha -1 ) Maize grain yield (kg ha -1 ) Continuous maize a2916.7a979.2a1125 Continuous maize b4270.8bc2625.0b2021 Native bush-maize40-*3083.3ab-*2313 Mucuna-maize40-†3437.5ab-†1563 Peanut-maize40-‡5062.5c-‡2042 LSD (0.05)

10 Experiment 2 Effects of nitrogen and phosphorus fertilizers on biomass production, soil organic carbon and maize grain yield Initiated in 2003 Initiated in x 3 factorial 3 x 3 factorial Factor 1: 3 N levels (0, 60 & 120 kg N ha -1 ) Factor 1: 3 N levels (0, 60 & 120 kg N ha -1 ) Factor 2: 3 P levels (0, 60, & 90 kg P 2 O 5 ha -1 ) Factor 2: 3 P levels (0, 60, & 90 kg P 2 O 5 ha -1 )

11 Materials and methods cont …. P source: single super-phosphate applied annually; P source: single super-phosphate applied annually; N source: Urea N source: Urea Tillage: no-till in 2004, 2005 & 2006 Tillage: no-till in 2004, 2005 & 2006 Residues returned to soil annually Residues returned to soil annually

12 Measurements Soil carbon measurements in 2003, 2005, 2006 Soil carbon measurements in 2003, 2005, 2006 LAI LAI Biomass accumulation and partitioning Biomass accumulation and partitioning Tissue analysis for N and P concentrations; Tissue analysis for N and P concentrations; End of season total biomass End of season total biomass Grain yield Grain yield

13 Effect of nitrogen and phosphorus fertilizers on crop residue returned to the soil TreatmentCrop residues returns (kg ha -1 ) N rate (kg ha -1 ) LSD (0.05) P rate (kg P 2 O 5 ha -1 ) LSD (0.05) Interaction****NS

14 Effect of nitrogen and phosphorus fertilizers on soil organic carbon changes with time TreatmentsSoil organic carbon (%) N rate (kg ha -1 ) LSD (0.05)NS P rate (kg P 2 O 5 ha -1 ) LSD (0.05)NS 0.11 InteractionsNS

15 Effect of nitrogen and phosphorus fertilizers on maize grain yield TreatmentMaize grain yield (kg ha -1 ) N rate (kg ha -1 ) 0502a479a201a882a b2063b1570b2056b c3340c2053c2646c LSD (0.05) P rate (kg P 2 O 5 ha -1 ) 0993a1320a567a1125a b2292b1625b2285b b2271b1632b2174b LSD (0.05) Interaction*** *

16 Experiment 3 On-farm evaluation of cropping systems and fertilizer on maize productivity and soil carbon Locations: 2 villages – Piisi and Nakor Locations: 2 villages – Piisi and Nakor Treatments Treatments - Continuous maize + 30 kg N ha -1 - Continuous maize + 80 kg N ha -1 - Peanut – maize rotation + 40 kg N ha -1 Replications: 15 farmers Replications: 15 farmers

17 Effect of cropping system and fertilizer on biomass production and soil carbon changes on some farmers’ fields Farmer Cropping system N rate (kg/ha) Residue returned (t ha -1 ) Soil carbon (%) Puri† Continuous maize ± ±0.02 Continuous maize ± ±0.02 Peanut/maize ± ±0.02 Naamori† Continuous maize ± ±0.02 Continuous maize ± ±0.03 Peanut/maize ± ±0.03 Dramani‡ Continuous maize ± ±0.02 Continuous maize ± ±0.02 Peanut/maize ± ±0.02 Marcel‡ Continuous maize ± ±0.03 Continuous maize ± ±0.03 Peanut/maize ± ±0.02 † = Incorporated residues ‡ = Did not incorporate residues

18 Effect of cropping systems and fertilizer on maize grain yield on some farmers’ fields Farmer Cropping system N rate (kg ha -1 ) Maize grain yield (kg ha -1 ) Mean Puri Continuous maize Peanut/maize Namore Peanut/maize Dramani Peanut/maize Marcel Peanut/maize


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