Dominated by intensive coffee monocultures for the last 30 years, farmers in the Central Highlands of Vietnam has been increasingly experienced with farming difficulties given resource degradation, market and climate uncertainties. In recent years, a number of farmers have diversified their coffee farms toward the forms of agroforestry: through integrating fruit and other crops into coffee farms. This study, by referring to the existing 10 agroforestry systems and 10 forestry ecological zones identified in the region for its approach, conducted in 20 communes throughout five provinces in the region at the coffee harvesting period in the end of 2018. In total, 249 farmers were identified through snowball sampling technique and successfully interviewed. Five major agroforestry systems are identified with sufficient sample size for statistical analyses. By detailed assessment of inputs used and revenue, this study proves that agroforestry systems strongly enhance farmer’s income. However, the success varies among the five studied provinces. Farmer’s technical know-how and their choice on 2nd crop made their agroforestry farming profit largely different. Given the fact that large percentage of land in the tropics is too dry, too steep, or too rocky to be classified as arable land which has been further problematic through increasing exposure to erosion resulting from unsustainable farming practices, often driven by intensive monocultures, efforts to promote agroforestry in Vietnam in particular and the tropics in general is thus needed, not only for surviving increasing population but also recovering and protecting the environment. In the situation of the Central Highlands of Vietnam, together with efforts in promoting agroforestry, a restructure of farming system needs to be considered in accordance with foreseeable difficulties in farming conditions, i.e., more water stress will be happened in certain provinces. These provinces should take a shift more toward less-irrigation dependent crops and reduce their dependence on coffee. These changes will create a better common guarantee for all farmers in coping with future uncertainties.

Two field trials were conducted at Giza Research Station, with split plot design with three replicates during the two successive summer seasons in 2012 and 2013. The aim of this study was to find out the effect of cotingen for covering seed by four treatments (zero, 7.5, 15 and 22.5 g kg-1 grain) and six nitrogen fertilizer levels (control, 30, 60, 90, 120 and 150 kg fed.-1) on maize yield and yield attributes of single cross 10 cultivar. Stepwise multiple linear regression analysis was used to determine the importance of yield components and to predict the yield under different levels of nitrogen and cotingen rates. Nitrogen levels exhibited significant effect for all studied traits, while cotingen were significant for100-kernels weight; shelling% and grain yield traits only. The interaction between cotingen and Nitrogen was significant for row per ear, shelling% and grain yield. Meanwhile, stepwise linear regression analysis showed that 100-kernels weight, number of kernels per row and shelling% were the most important contributing traits to yield (R2 = 82.11%). The nitrogen rates for maximum yield derived from the four statistical models (linear, logarithmic, quadratic, and exponential) describing the response of yield, using the R2statistic to select a model, which shows how each of the models fits the data. The quadratic model best described the yield responses observed in this study. Further confirms the role of nitrogen and cotingen fertilizers in increasing yield production in maize. The 5th N rate under 3rdcotingen (120 Kg fed-1 + 22.5 and 15g kg-1 grain) produced the highest yield being 34.70 and 34.65 ard. fed-1 over all treatments. This is very close to recommendations. The 4th N (90Kg fed-1) rate under any cotingen level produced higher yield than any nitrogen rate only. Economically, considering optimum N fertilization rate, 105.18 Kg fed-1 nitrogen and 22.5 g kg-1 grain cotingen was the most reasonable level. This is considerably below the current recommendation. Therefore, results confirmed that higher cotingen treatment decreased the optimal nitrogen and increased the yield.