Parthenium hysterophorus (Asteraceae), of South American origin, is considered to be one of the worldÕs most serious invasive plants, invading Australia, Asia and Africa. As part of an international collaborative project, this study attempted to improve the understanding of the geographical distribution of P. hysterophorus in eastern and southern Africa. The climate modelling program CLIMEX was used to assist in the selection of survey localities. Roadside surveys of the distribution of the weed were conducted in Botswana, Ethiopia, South Africa, Swaziland and Uganda. Prior to these surveys, only limited P. hysterophorus locality records existed; substantially more records were obtained from surveys. Most infestations were high density (>3 plants m )2 ). Distribution records were used to validate the CLIMEX model, which proved a useful tool. This study increased current understanding of the distribution of P. hysterophorus and developed a baseline from which to monitor future spread and abundance of P. hysterophorus. Additional surveys are required in other countries in Africa which are predicted by CLIMEX to be at risk. This will enhance integrated management decisions for the control of a weed which has implications for food security and human health.

Core Ideas Conservation agriculture (CA) was evaluated in Ethiopia.Short and medium‐term effects of CA depends on initial soil properties.Improved water infiltration and crop yield can occur in the short‐term.Yield increase in the short‐term is less likely with moderate soil in humid areas.Canopy reflectance can be used to study in‐season effects of no‐till and residue. Conservation agriculture (CA) is common globally but not in tropical Africa, including Ethiopia. Conservation agriculture was evaluated at Bako (short‐term CA study) and Melkassa (medium‐term CA study) in Ethiopia for effects on crop yield and soil properties. Results showed the rate of water infiltration was 16% more at Bako and 15% less at Melkassa for conventional practice (CP) (tillage plus crop residue removal) compared with CA (no tillage plus residue retention). Time‐to‐pond was doubled and soil penetration resistance was 7 kP less for the 0–0.1 m depth with CA maize (Zea mays L.)–dry bean (Phaseolus vulgaris L.) rotation compared to CP maize monoculture at Melkassa. Soil organic C for the 0–0.05 m soil profile was 16 g kg−1 with CA compared with 12 g kg−1 for CP and early maize growth was slower with CA compared with CP at Melkassa. Maize stover yield was 10.14 Mg ha−1 for CP compared with 9.01 Mg ha−1 for CA in 2015 at Bako, but maize yields were greater with CA at Melkassa in 2016. Monoculture and intercrop dry bean, respectively, had 40 and 32% more grain yield with CA compared to CP in 2016 at Melkassa. It was concluded that medium‐term beneficial effects of CA on soil properties and crop productivity can be expected at Melkassa, but any short‐term benefits of CA at Bako were uncertain.

The productivity of tef-sunfl ower intercropping, with or without fertilizer, was assessed by fi eld trials in northeast Ethiopia. Mixed planting of 10-50% of sunfl ower with tef had yield advantages of 20-39% and 58-77% at two different sites. The crop proportions giving the greatest yield benefi t varied between the sites. The greatest net income benefi ts were US$515 ha −1 and US$69 ha −1 at the two sites. ConclusionMixed cropping of tef and sunfl ower increased yields and land productivity, and improved the monetary return, and can thus be recommended. However, the optimum level seems to depend on the variety and location: in this study, mixed cropping of sunfl ower with tef at 50% gave signifi cantly better returns at Sirinka, but at Kobo there were no signifi cant differences in net income from the fi ve mixed-cropping treatments.

Parthenium is widely distributed across the uncropped areas of the tropics. It has slowly encroached into many crops and causes considerable yield loss. It heavily infests sorghum, which is widely cultivated by the resource-poor farmers in Africa and Asia. Its interference and management in sorghum in these cropping systems is not well understood. Therefore, this experiment was undertaken to determine the appropriate parthenium management techniques to use in sorghum crops. All the studied weeds, in combination with parthenium, offered greater competition to sorghum than parthenium alone. Similarly, under a composite stand of weeds, parthenium was inferior in competitiveness to the other weeds until 60 days after sowing (DAS); by 90 DAS, it could accumulate a higher dry weight due to its consistent growth. A pre-emergence treatment of atrazine (0.75 kg ha -1 ) with wheat straw mulch (5.0 t ha -1 ) brought about a consistent and significant reduction in the parthenium growth and, consequently, increased the sorghum yield by 90.8%. Cowpea intercropping with and without pendimethalin (1.0 kg ha -1 ) as a pre-emergence treatment could not control parthenium between 0 and 60 DAS, but could reduce the parthenium growth during the later period of 60-90 DAS, which resulted in a significant increase in sorghum growth. These intercropping treatments increased the sorghum grain yield by 156.2% and 142.4%, respectively, over the unweeded control and by 18.5% and 12.1%, respectively, over the weed-free control. These treatments also promoted a higher uptake of N, P, and K by the sorghum crop.Thus, cowpea intercropping was the most effective method for parthenium management vis-à-vis sorghum yield improvement, followed by cowpea intercropping with pendimethalin and then by atrazine as a pre-emergence treatment with wheat straw mulch.

The imbalance between the crop production and population growth is currently the major issue in southern Ethiopia. To feed the growing population, increasing the production of food through growing more crop types in the same field as an intercropping is the right strategy. The current study was aimed at evaluating the effect of sorghum-legume intercropping and its residual effect on yield of sorghum. The land equivalent ratio was calculated for sorghum intercropped with pigeon pea and cowpea. Intercropping sorghum with pigeon pea and cowpea increases the land productivity as its Land Equivalent Ratio is greater than 1. In both cases, the land equivalent ratio is greater than 1 indicating the benefits of intercropping. The residual effect of sorghum intercrop with legumes was evaluated on the yield of sorghum. Although there was no statistically significance differences on yield and yield component of sorghum, sorghum planted on the plot of pigeon pea and cowpea sole has 44.6% and 27.8% yield advantage relative to sorghum alone respectively. Planting sorghum under sorghum-cowpea intercropped condition increase the yield of sorghum by 41.8%. The result also shows 74.0% sorghum yield change was observed when planted after intercropped condition of sorghum with pigeon pea. The productivity of sorghum also increases when planted on the plot of sole legume. The current finding in general shows that legume crops contributed to the yield of sorghum either intercropped with legume or grown up using residual contribution of legumes after a year. Therefore, for maximum sorghum production farmers in the area should plant either as intercrop or after residual effect of legumes. Int. J. Agril. Res. Innov. Tech. 9(2): 62-66, December 2019