A field experiment was conducted to assess the effects of combined application of farm yard manure (FYM) and inorganic NP fertilizers on soil physico-chemical properties and nutrient balance in a rain-fed lowland rice production system in Fogera plain, northwestern Ethiopia. The study was carried out during the main cropping seasons of 2010 and 2011. Twenty-seven treatments comprising a factorial combination of three rates of FYM (0, 7.5, and 15 t·ha ) were tested. The experiments were laid out as a randomized complete block design with three replications. Bulk density, organic matter content, and available water holding capacity, total N, and available P of the soil were measured just after harvesting the rice crop. Results showed that application of 15 t·FYM·ha −1 significantly increased soil organic matter and available water holding capacity but decreased the soil bulk density, creating a good soil condition for enhanced growth of the rice crop. Application of 15 tFYM·ha −1 increased the level of soil total nitrogen from 0.203% to 0.349%. Combined application of 15 t·ha −1 ·FYM and 100 kg·P 2 O 5 ·ha −1 increased the available phosphorous from 11.9 ppm to 38.1 ppm. Positive balances of soil N and P resulted from combined application of FYM and inorganic N and P sources. Application of 15·t ha From the results of this experiment, it could be concluded that combined application of FYM and inorganic N and P fertilizers improved the chemical and physical properties, which may lead to enhanced and sustainable production of rice in the study area.

Background: Nitrogen is one of the most important nutrients limiting yield of bread wheat in Ethiopian highlands. Application of a large amount of N fertilizer has been a method of increasing yield in the study area which is costly and can cause environmental pollution. Therefore, a field experiment was conducted for two consecutive years (2014 and 2015) to evaluate the effect of N application rates on grain yield, nitrogen uptake and N use efficiency of bread wheat varieties. The treatments consisted of a factorial combination of four rates of nitrogen (0, 120, 240 and 360 kg ha −1) and three popular wheat varieties (Menze, Tsehay and ET-13) in a randomized complete block design with four replications. Results: The two-way interaction of year and N rate, N rate and variety significantly affected grain nitrogen concentration. The interaction of year and variety and N rate and variety affected grain and straw nitrogen concentrations, respectively. The three-way interaction of year, N fertilizer rate and variety significantly affected (P < 0.01) grain yield, grain and total nitrogen uptake, agronomic efficiency, agro-physiological efficiency and apparent recovery efficiency. The highest grain yield (5718.32 kg ha −1) was obtained from variety Menze at N rate of 360 kg ha −1 in 2015 which was statistically at par with the application of 240 kg N ha −1 and with variety Tsehay at N rate of 240 and 360 kg N ha −1 during the same growing season. The highest grain and straw (2.7 and 0.35%, respectively) nitrogen concentration were produced by variety Tsehay at N rate of 360 kg ha −1. The highest apparent nitrogen recovery efficiency was recorded for variety Tsehay at N rate of 120 kg ha −1 in both growing seasons. Conclusion: Hence, it could be concluded that varieties Menze and Tsehay produced the highest grain yield followed by variety ET-13. All wheat varieties tested did not show a significant variation in most of the nitrogen use efficiency parameters, and these efficiency parameters decreased with the increasing rate of N beyond 120 kg ha −1 in both growing seasons.

Background: Potato plays a great role for the achievement of food security program due to its plasticity to environmental conditions and yielding capacity. However, its productivity is far less than other countries due to constraints threatening subsistence farms in Ethiopia. Therefore, potato production practices by smallholder farmers were assessed in Wolaita zone of southern Ethiopia to identify major factors constraining production of the crop. Data were collected at two stages, i.e., at a pilot survey and the time of basic data collection. Descriptive statistics, multiple linear regression, and index ranking were used to analyze the data. Results:The descriptive statistical revealed that smallholder farmers have very small land (about 0.5 ha per household). Low access to and high prices of seed tubers of improved potato varieties (>0.25 USD kg −1 seed tubers) and scarcity of information on good fertilizer management practices for producing the crop with only a blanket rate of 147 and 135 kg ha −1 of urea and diammonium phosphate, respectively, limit potato production in the area. Furthermore, prevalence of diseases and low market prices of tubers at harvesting, but too expensive during planting period are the major constraints of potato production in the zone. In addition, results of the multiple regression analysis indicated that the occurrence of natural hazards, seeding rate and expensive price of improved seed tubers were important factors significantly influence potato productivity in Wolaita area. Likewise, disease problems, low market price of potato at harvesting time, storage problems, and lack of seed tubers were the four major constraints identified by index ranking. Conclusions:Results of this study revealed that potato production is constrained by a number of factors among which diseases, storage problems, low market prices of tubers at harvest, and insufficient quality seed tubers for planting were the four major constraints challenging potato production in the study area according to the index ranking method.

Background: Bread wheat is an important staple and cash crop grown by smallholder farmers in the central highlands of Ethiopia. However, the productivity of the crop is constrained by low soil fertility and poor nitrogen fertilizer management in the area. For example, there is limited information on optimum rates and timing of nitrogen fertilizer application in the area. Therefore, a field experiment was conducted for two consecutive years (2014 and 2015) under rain-fed condition to determine the effect of N fertilizer rate and timing of application on grain yield and nitrogen use efficiency of bread wheat. Factorial combinations of three N levels and five application times plus one control were laid out in a randomized complete block design with four replications. Results: The optimum grain yield (6060.04 kg ha −1) was recorded when 240 kg N ha −1 was applied ¼ at sowing, ½ at tillering and ¼ at booting, and it showed no significant additional response to N fertilizer above this rate. Higher N level (360 kg N ha −1) always increased N content in the grain and nitrogen uptake by wheat crop. The best recovery of nitrogen (59.74%) by wheat was found when 120 kg of nitrogen was applied (¼ at sowing, ½ at tillering and ¼ at booting). The nitrogen use efficiency traits decreased with increased N rate (120-360 kg N ha −1) indicating poor N utilization. The split application of nitrogen (¼ at sowing, ½ at tillering and ¼ at booting) produced the highest nitrogen use efficiency traits. Conclusion: The application of 240 kg N ha −1 in three split doses (T 5) was required to obtain optimum wheat yield. In addition, increasing the rate of nitrogen beyond 120 kg N ha −1 decreased nitrogen use efficiency traits.

A previous study demonstrated that cabbage was P efficient compared to carrot and potato. However, calculating plant P uptake by a mechanistic simulation model based on P transport by diffusion and mass flow, P uptake of roots according to the Michaelis‐Menten kinetics, and morphological root characteristics including root hairs, revealed that these parameters could explain only 2/5 of the total P uptake of cabbage, but 4/5 of that of carrot and potato (Dechassa et al., 2003). Therefore, it was hypothesized that a higher root exudation of organic anions may enhance P mobilization and hence P uptake of cabbage. The objective of this research was to determine root exudation of organic anions by the three species, and to investigate the influence of plant age and dark/light period on organic‐anion exudation by cabbage. Experiments were conducted in a growth chamber in nutrient solution with or without P. Organic anions were determined in root exudates and in root tissue. With cabbage and potato, P deficiency induced exudation of citrate and succinate, respectively. Citrate‐exudation rate of P‐deficient cabbage plants was correlated with accumulation of citrate in root tissue. In contrast, high succinate‐exudation rates in potato were not correlated with an increased concentration in root tissue. For carrot, no change was observed in the exudation of any of the organic anions in response to P deficiency. The results also showed that succinate‐ and citrate‐exudation rates of cabbage roots increased with increased plant age. There was also a significant increase in exudation rates of organic anions of cabbage roots during the light period of the day. It was concluded that cabbage had the ability to exude large amounts of citrate in response to P deficiency by which it can additionally enhance its P‐uptake efficiency, whereas carrot and potato showed little evidence of possessing such a mechanism.