Evaluation of legume shrubs improved fallow for abandoned agricultural land rehabilitation

The experiment was conducted on abandoned agricultural land at Bena-Tsemay District, Southern Ethiopia. It was designed to evaluate legume shrubs growth performance, and its potential for soil fertility enhancement through improved fallow practice. The results of the current study showed that the growth performance of legume species reveals variation in different growth parameters. The mean height of Sesbania sesban was significantly higher than the other species except for Senna siamea. Senna siamea recorded the highest mean stem diameter followed by Sesbania sesban, 3.47 cm, and 2.86 cm, respectively. Legume shrub species for soil fertility enhancement under improved fallow showed an increase in soil pH, organic carbon, organic matter, phosphorus level, available potassium, and total nitrogen during the growth period. Sesbania provides a large amount of nitrogen (2.91 t ha- 1) within two years fallow period, linked with the carbon to nitrogen ratio (11.22) having better mineralization potential. The growing of promising legume shrub species as an improved fallow practice has an important contribution in the restoration process of abandoned agricultural land and used as an option to grow crops in a rotational cropping system. Int. J. Agril. Res. Innov. Tech. 10(1): 64-70, June 2020

A Slash-And-Mulch Improved-Fallow Agroforestry System: Growth and Nutrient Budgets over Two Rotations

Agroforestry systems are important, globally affecting 1.2 billion people and covering 0.6 billion hectares. They are often cited for providing ecosystem services, such as augmenting soil fertility via N accumulation and increasing soil C stocks. Improved-fallow slash-and-mulch systems have the potential to do both, while reducing nutrient losses associated with burning. In the absence of burning, these systems also have the potential to grow trees through multiple rotations. This project collected soil, mulch, and biomass data over the course of one 9-year crop-fallow rotation and the first two years of the second rotation. A split-plot design was used to assess the effects of P + K fertilization and inclusion of an N-fixing tree species, Inga edulis, on crop and tree biomass production. Fertilization increased growth and nutrient accumulation during Rotation 1 by an average of 36%, ranging from 11% in Parkia multijuga to 52% in Ceiba pentandra. Residual P + K fertilization improved tree and crop growth 20 months into Rotation 2 by an average of 50%, ranging from 15% in Cedrela odorata to 73% in Schizolobium amazonicum. The improved-fallow slash-and-mulch system increased the rates of secondary succession biomass accumulation (11−15 Mg ha−1 yr−1) by 41–64% compared to natural succession (7–8 Mg ha−1 yr−1). Furthermore, P + K fertilization increased secondary-succession biomass accumulation by 9–24%. Nutrient accumulation through biomass production was adequate to replace nutrients exported via crop root and timber stem harvests.

Adoption and Impact of the Improved Fallow Technique on Cotton Productivity and Income in Zambia

An improved fallow is a soil fertility agroforestry technique that has commonly been used in the staple maize production systems of Zambia and sub-Saharan Africa. Several studies have assessed the adoption and impact of the improved fallow on maize production. Generally, it has been observed that though the improved fallow does increase maize yields, its efficacy on welfare in terms of increased income is low. The use of the technique on cash crops that could significantly contribute to household welfare has rarely been investigated. This study assessed the factors affecting the adoption and impact of improved fallows on a commonly grown cash crop, cotton, in the cotton growing provinces of Zambia. The study used a sub sample (N=1206) of the nationally representative 2014/15 Rural Agricultural Livelihoods Survey (RALS) data which was randomly collected by the Indaba Agricultural Policy Research Institute (IAPRI) and Central Statistical Office (CSO) of Zambia. The determinants of improved fallow adoption among the cotton farmers were examined through the use of the probit model while the impact of the technique on cotton production and income was evaluated by using the propensity score matching and the endogenous switching regression models. Among the socioeconomic factors significantly increasing the probability of improved fallow adoption included: increases in age, education level, and per capita productive assets of the farmer, in addition to the area under cotton production and the distance of the homestead to the market. Institutional factors found to increase the farmer’s likelihood of adopting the improved fallow in the cotton production systems included; farmer membership to a cooperative, receiving improved fallow seedlings from the government projects and having information on agroforestry tree species. On the other hand, an increase in land size per capita was found to negatively affect the likelihood of improved tree fallow adoption. Impact estimates showed significant cotton yield and income increases as a result of adopting the technique. The continuous provision of information on relatively new techniques such as the improved fallows preferably in farmer organized groups, and support towards the provision of the technique’s planting materials are some of the areas requiring government and NGOs attention. In addition, the study recommends that the farmers’ formal education level should be enhanced and that improved tree fallows should also be explicitly promoted on cash crops that have similar agronomic requirements to maize such as cotton.