ABSTRACT

  Soil quality protection under intensive land use and fast growing economic development has become a major challenge for sustainable resource use in developing countries such as Nigeria. Soil quality is fundamentally important in agricultural production and soil fertility is becoming a central issue in decision on food security. Intercropping is the most common practice in traditional agricultural systems in the continent. Declining soil quality is emerging as an environmental and economic issue of increasing global concern. This is because degraded soils are becoming prevalent due to intensive use and poor management. Declining soil productivity due to poor soil quality (such as N and P deficiency and low organic matter) has been a major limiting factor to food production in Nigeria.Evaluation of Maize-Desmodium -Soybean cropping effect on soil quality and crop yields in Alfisol of Northern Guinea Savanna, Nigeria was conducted in 2014 and 2015 cropping seasons at the Institute for Agricultural Research (IAR) Farm, Ahmadu Bello University, Zaria. The trial was established in 2014 and repeated in 2015 at the IAR Meteorological site located between latitude 11o11‟19.3”N and Longitude 7o37‟02”E in the Northern Guinea Savanna ecology of Nigeria. The experiment was laid out in a Randomize Complete Block Design (RCBD) and replicated three times. Plots (M), (D) and (S) were planted with sole Maize, Desmodium and Soybeans respectively. Plots with (MS) and (MD) were inter cropped while plots MS 2:4 and M:D 2:4 were planted two strips of maize to four rows of Soybeans and strips of two maize to strips of four rows of Desmodium respectively. The variety of soybean used was IITA-TGX-1951, Maize was SAMMAZ 14. Soil sample obtained were evaluated for soil chemical properties organic carbon (OC), available phosphorus (avail P), total nitrogen (TN), soil pH, and cation exchange capacity (CEC), physical soil properties bulk density (BD), soil moisture content (SMC) and mean weight diameter (MWD). Plant height, stover yield, maize and soybean grain yield were also measured. Results showed that in 2014, mean pH water was 6.37, mean pH CaCl was5.78, mean organic carbon was 5.23 gkg-1, mean total nitrogen was 0.66 gkg-1, and mean available phosphorus was 10.90 mg kg-1. Analysis from combing the two years shows that maize/Desmodium strip cropping best increase soil pH, OC and TN than other treatments. The soil available phoshorus was best increase under sole soybean. Average mean weight diameter (MWD) increased from 0.59 in 2014 to 0.99 in 2015 indicating a better aggregation across the treatments. However, treatment under maize/soybean intercropping (MS) had a higher MWD. Bulk density at 8 and 16 WAP were 1.54 Mgm-3 and 1.43 Mgm-3, respectively in 2014. Treatment under sole maize resulted in higher BD than other treatment at 8WAP and 16WAP. Best grain yield was under sole maize and maize/ Desmodium strip cropping in both years. Maize-Desmodiumintercropping resulted in higher grain yield in the first year than other treatments while sole maize gave higher yield in the 2015. Treatment under maize Desmodium strip improved soil chemical most quality while physical quality was best improved under sole soybean in this study. Generally, adoption of maize Desmodium stripandmaize-soybean intercrop favoured better soil chemical and physical properties relative to sole maize. The use of treatment maize Desmodium strip improved soil quality better than all other treatments. Amount of SOC sequestered under treatment maize soybean intercrop was significantly higher than other cropping systems and the least was under MD. Carbon sequestered in macro aggregates were higher relative to other aggregates. The total land equivalent ratio (LER) for intercropping and strip-cropping were 1.15 and 1.37 and showing 13 % and 27 % land saved in 2014 cropping seasons respectively and in 2015; the ratio was 1.21 and 1.37 and showing 17 % and 27 % land saved in 2015 cropping seasons, respectively.Maize yield were best improved under sole maize and maize/Desmodium intercropping. Adoption of maize/Desmodium strip cropping best improves soil quality.