Globally, a range of agronomic factors have been reported to have an impact on the performance of conservationagriculture (CA) and often determine its performance in relation to conventional agriculture (CONV). To assess this performance in Zimbabwe, 48 CA experiments were conducted by the International Crops Research Institute for the Semi-Arid Tropics in the semi-aridareas of southern Zimbabwe from 2004 to 2010, to calculate the weighted mean difference (WMD) through meta-analytical methods. The two CA practices, planting basins (Basins) and ripper tillage (Ripper), were compared with CONV. It was hypothesised that CA results improved yield compared with CONV and that the effect of CA practices on yield is affected by soil type, rainfall amount and distribution and selected management practices, which included rates of inorganic fertilisers and manures and mulching. Basins were superior to CONV in 59% of the experiments and the overall effect was significant (p < 0.001). The effect of Ripper was non-significant. The hypothesis that CA practices result in improved maize grain yield over CONV was accepted for Basins. The WMD for experiments conducted on sandy soils was 0.365 t ha −1 for Basins and 0.184 t ha −1 for Ripper, and in both cases was significant (p < 0.05). For clay soils, only the WMD for Basins was significant. A higher rainfall regime (500–830 mm) resulted in a lower WMD for Basins (0.095 t ha −1 ) and Ripper (0.105 t ha −1 ) compared with 0.151 t ha −1 for Basins and 0.110 t ha −1 for Ripper under lower rainfall (320–500 mm). The overall effect of Basins under the higher rainfall regime was not significant. There was better yield performance for Basins when the rainfall was well distributed; the reverse was noted for the Ripper. The application of 10–30 kg ha −1 of N (micro-dose range) resulted in a higher WMD for Basins than zero N application. Without N application, the WMD of Basins was not significant. For zero manure application in Basins, the WMD was 0.043 t ha −1 compared with 0.159 t ha −1 when manure was applied. The application of mulch depressed the WMD in Basins by 44% and Ripper by 89%. The hypothesis that yield performance under CA is influenced by soil type, rainfall amount and distribution, inorganic fertiliser and manure application was accepted.
not zero as people attach some value to leisure time ( CIMMYT, 1988 ). The four critical parameters that drive net economic effects of switching to CA are the yield gain advantage, and the cost elements of equipment, herbicides and labour. While we are conﬁdent of the yield impact estimate because of the considerable number of studies that quantiﬁed CA yield responses, and the relatively large samples and wider geographic coverage (different rainfall, soil type), data on the accompanying labour changes is scanty. The paucity of labour use data could be due to the difﬁculty of measuring labour. In the current paper, a single study by Siziba (2007) , which is based on only seven on-farm trials within one locality in one district, was relied on for labour data. However, through the breakeven curves, the analysis allows evaluation of economic effects under different yield and labour response levels. Though at the averages of the economic effect equation parameters (maizeyield responses, prices, and labour use changes) the returns were negative, there are still conditions under which returns could be positive. These would generally be cases where yield responses are maximised and labour increases minimised. The yield gains may be increased by good farmer management or where soils are fertile but moisture is very limiting such in Natural Region IV. Labour increase can be minimised under biophysical environments where weed pressure is naturally low. There are many farmers who may be able to enjoy this niche and realise positive returns. Such prospects are more likely with the ripper in Natural Region IV where best NPVs were realised.
deeper zones in the soil or enrichment through stem fall and subsequent decomposition. Soil are an integral component of agriculture and serve as medium for eco-biological, chemical and physical processes. Over burdening of soils as a natural resource have always been serious issues. The need to effectively manage soil (store house of nutrients) in order to achieve optimum productivity and enhance agricultural productivity to support increasing population is necessary. The challenge of producing enough food for ever increasing population has been one of the many issues facing mankind for a long time (Yakubu, 2010). Semi-arid region of Nigeria, especially areas around Borno, are known for their low soil fertility and degradation mostly influenced by erosion and desertification (Abdu, 2013). Socio economic problem especially poverty is a key issue in the region where rural farmer in the area lack the capacity to tackle the problem of low soil fertility.
The principles of CA minimum soil disturbance and mainte- nance of a mulch resulted in reduced mineralisation (Fig. 2) resulting in low yields whilst a combination of the principles resulted in high mineralisation and yields comparable to conventional plough minus mulch (Fig. 3). Fertiliser application resulted in yield bene ﬁ ts regardless of tillage or mulch application particularly when moisture was not limiting. The potential bene ﬁ ts of the tillage, mulch application and fertility amendment applica- tion on crop productivity and soil N dynamics are related to the management intensity individual farmers can achieve. The use of mineral fertilisers is key to production yet their widespread use by smallholder farmers remains low as availability in rural areas remains a key constraint to their use as well as their cost remains prohibitive. With over 40% of households in semi-aridZimbabwe having access to draught animals (ZimVac, 2012), the use of the ripper may provide a solution to curb the chronic labour demand associated with land preparation in manual forms of in smallhold- er communities. However, only a few equipment manufacturers have been producing ripper tine attachments for the mouldboard plough and these require pre- ﬁ nancing for production. There are poor market linkages between smallholder farmers market
Farmers use a range of planting dates and plant at almost any op- portunity because of the rainfall pattern, input access, and the avail- ability of draught power and labour ( Milgroom and Giller, 2013 ; Rurinda et al., 2013 ; Nyagumbo et al., 2017 ). Conservationagriculture (CA) can provide a major beneﬁt by reducing the tillage requirement, thus allowing farmers to plant on time at the start of the season. Nyagumbo et al. (2008) indicated that in Zimbabwean cropping sys- tems, the major beneﬁt of CA for crop yields comes from timely planting and not from the speci ﬁc tillage employed. The onset of the ﬁrst rains stimulates soil microbial activity resulting in a peak of soil N mineralisation ( Birch, 1960 ). This so-called mineral N ﬂush (Birch ef- fect) is usually of short duration due to losses through leaching, deni- tri ﬁcation, volatilisation and plant uptake ( Chikowo et al., 2003 ; Bognonkpe and Becker, 2009 ). The magnitude of the mineral N ﬂush is dependent on a number of factors which include the quantity and quality of organic matter ( Franzluebbers et al., 1995 ), the occurrence and duration of dry spells at the onset of the rainy season and rainfall variables such as the intensity and quantity of rainfall ( Bognonkpe and Becker, 2009 ). Planting early with the ﬁrst rains may be beneﬁcial to crops if the planting coincides with this mineral N ﬂush or risky if these ﬁrst rains appear to be a false start to the cropping season. Such false starts are not uncommon in semi-aridareas, as early-season rains are commonly followed by a dry spell, which is detrimental to crop es- tablishment ( Chikowo, 2011 ).
Tillage practices break up high density soil layers below, improve water holding and infiltration in the soil, enhances root growth and development, and increase crop production potentials. To meet the food requirement of ever increasing human population, there is a great need of high crop productivity rate, which is only possible when soil is properly ploughed in the rain-fed areas and to conserved moisture in the subsoil. Proper tillage practices and moisture conservation is required for good yield in semi-arid zone. Now a days about 70-75 % of land in the tribal areas is simi-arid only one crop that is wheat is raised. But there is need to grow more food crops in arid zone due to explosive increase in population in tribal belt as well as Khyber Pakhtunkhwa. This is a 21 st century which is the century of
The precipitations are generally characterized by their weakness, their irregularity and a bad distribution spatial-temporal from 180 mm/year in the plain to 600 mm/year in the north in the High-Atlas peak. On the plain, the precipitation decrease from north to the south and from the west to the east recording averages of about 280 mm on the plane of Souss, 265mm on the plane of Massa and 180 mm on the plane of Tiznit in the south (MEMEE 2015). The Humid season starts from November to March, when the region gets 70 to 75% of annual rain. The dried season, between April to October, the region receives 30% of annual rain. The average of the raining days was about 30 days per year in the plain and 60 days per year in the High Atlas Mountain. The quantity of the rain varies from one year to another, so the precipitation of the most humid year reach up to three times the annual average and until 15 times of the driest year. The economy of Souss-Massa is based on marine fishing, the tourism and especially the agriculture. The region presents a potential irrigable lands, about 250000 ha. This sector is dominated by a modern agriculture with irrigated areas of about 143000 ha, principally situated on the plains of Souss (114310 ha) and Massa (27105 ha). The forage crops are essentially constituted of forage corn and alfalfa which occupies an irrigated area about 21844 ha. So, the livestock farming represents 28 % of the agricultural production of the region (MEMEE, 2015). Conditions of breeding: The Holstein of the agriculture (AG) cooperative (COP) «COPAG» contains about 80000 heads in which 40000 milk cows are distributed in the four provinces of Souss-Massa region. This herd is the result of the heifer born locally and some heifer introduced in the region either from other region of Morocco or imported from France, Germany, Canada and Netherlands. The most used mode of reproduction at the level of member farms is the artificial insemination carried out by a team of inseminators of «COPAG». The seeds were imported from France, Canada, Germany and USA. In case of the failure of the third artificial insemination, the conceptions were assured by natural service by brood bulls, selected on the basis of their conformation and the milk production of their mothers.
Small-scale rain-fed agriculture is the main livelihood source in arid and semi-aridareas of SSA. The yield levels in such farming systems are very low especially during years of severe drought. In some cases a little surplus is realised which is then saved for other household needs. In response to the low yields, smallholder farmers diversify their sources of income. The diversification is also a way to accumulate wealth. However, the security of the livelihoods of smallholder farmers in this environment remains closely linked with the productivity levels of the local agro-ecological zones, which are hindered to a large extent by water availability (Millennium Ecosystem Assessment [MEA] 2005; Stringer et al. 2009). The arid and semi-aridareas are characterised by high atmospheric evaporation and highly variable spatial and temporal precipitation that makes rain-fed farming a risk economic activity (Nyakudya & Stroosnijder 2011). The erratic rainfall and frequent droughts make the capacity for coping with temporal water shortages important for smallholder farmers (Enfors & Gordon 2008; Stringer et al. 2009).
Rainfed smallholder agriculture in semi-arid environments of sub-Saharan Africa faces many challenges. Productivity of the smallholder ag- ricultural systems has been on the decline in recent years. Conservationagriculture practices have a potential of steering the smallholder agri- cultural systems of sub-Saharan Africa to grea- ter and more sustainable levels. This study was designed to calibrate the APSIM model so that it could be used as a tool for understanding the long term impact of conservationagriculture techniques (mulching, tine ripping and planting basins) on the productivity of smallholder sys- tems under semi-arid conditions. The APSIM model predicted reasonably well the seasonal and mulching effects on maize production on sand and clay soils. Under these semi-arid conditions the use of 10 kg·N·ha –1 is preferable under both conventional and basin tillage sys- tems. Planting basins offer a better chance of getting maize grain yield than the conventional system in southern Zimbabwe at N quantities ranging from 0 kg·ha –1 to 52 kg·ha –1 . This mod- elling exercise suggested that smallholder farmers are still prone to complete crop failure in some years despite the use of available con- servation agriculture systems.
In Zimbabwe and Malawi, negative effects of CA adoption on food security were observed though these were not statistically significant. For example, in Zim- babwe CA adoption was estimated to result in a reduc- tion (ATE1) of 2.05 in the FCS among farmers who were using CA. Positive results were observed in Mozambique where CA adoption resulted in an improvement in the FCS by 5.486 among CA users (ATE1), and this effect was statistically significant (P < 0.1). Possible reasons for the insignificant of CA impact on food security in Zimbabwe and Malawi could include the small land areas currently devoted to CA, and the failure to implement the full complement of practices necessary to set off the biophys- ical process that are expected to drive yield increases. For example, farmers due to constraints imposed by the bio- physical, institutional and socio-economic environment often fail to achieve meaningful residue retention and/ or incorporate herbicides to control weeds . A possible reason for effectiveness of CA in Mozambique could be due to the fact that often CA is being promoted together with other better cropping management practices such as timely weeding and improved seed varieties, which are poorly practiced by the generality of farmers in a country just emerging from a war period.
Maize ( Zea mays L.), also locally known as efun in Eritrea, ranks third after sorghum and pearl millet among summer food grains and fifth among all food grains after sorghum, pear millet, wheat and barley in both area and production. The productivity of this crop in Africa in general and Eritrea in particular is much lower than its average productivity (4472 kg/ha) in the world. The low productivity of maize in Eritrea is attributed to the lack of quality seeds of high yielding varieties, moisture stress due to low and erratic rainfall, high tempera- ture, low soil fertility, competition by weeds, inappropriate tillage and sowing system, lack of nutrient supplying capacity of the soil and timely non availability of the fertilizer to the farmers . In addition to these, the degraded land with limited soil moisture availability at critical stages of crop growth is other major constraints of low productivity. Among these moisture stresses due to low and erratic rainfall, lack of appropriate methods of soil moisture conservation, lack of adaptable varieties to moisture stress and their optimum population density are the dominant in reducing its average productivity. In Eritrea, maize is pro- duced in very marginal areas like highland and thus the production is not suffi- cient to meet the aggressive demand by the consumers.
The combination of tied ridges, flat bed, farm yard manure, nitrogen fertilizer, maize mono crop and maize cow pea intercrop resulted to increased maize vegetative growth and yield components. The use of tied ridging was more effective in promoting vegetative growth during the long rains 2015 when the rainfall was low, whereas flat bed planting was more effective during the short rains 2014 when the amount of rainfall received was slightly higher. Therefore, in order to promote vegetative growth, there is need to apply nitrogen fertilizers in addition to conserving soil moisture. From the findings in this study, it may therefore may concluded that, in maize production, soil moisture conservation, fertilizer input application and cropping systems are key aspects to be considered in order to improve maize yields. The use of maize mono crop under tied ridges when the rainfall was below average improved the yields. Therefore, from the findings of this study, it may be recommended that, during the seasons of low rainfall, farmers in the study area may consider adopting maize mono crop with application of 20kgN/ha under tied ridging. Also, use of tied ridging in the study area could be restricted only to seasons of low rainfall because they are less effective in seasons with high rainfall. In addition, it is important to integrate various soil and water management practices since adopting a single technology does not exploit its potential. Variations in seasonal rainfall should be put into consideration when recommending soil and water management practices in semi-aridareas. .
Due to increasing population the fibers and food demand is increasing and on the other hand the per unit irrigated area water availability is decreasing. The demand of maize is expected to be increase several folds as the population is increasing. Thus, circumstances demand sustainable increased of crop yield per unit area with scare water resources. The research was carried out at Agronomy Research Farm, The University of Agriculture Peshawar, during May 2017.The research was laid out in RCBD with split plot arrangement having 4 replications. Deficit Irrigations (Full irrigation (10 irrigations), one irrigation missing at six leaves stages, twelve leaves stage, flowering stage and grain filling stage) were allotted to main plots, while planting methods (Ridge, Flat and Broadcast)were allotted to sub plots. Deficit irrigations had a significant (P≤0.05) effect on all parameters excluding girth diameter and grain rows ear -1 . Full irrigation (10 irrigations) had significantly more leaf area plant -1 (6916.90 cm 2 ), grain
Specialized sensors have become an important component for crop monitoring, particularly for improving precision, efficiency, and throughput in phenotyping . Remote sensing indexes have largely demonstrated their various applications in agriculture, including yield prediction, stress detection, and control of plant diseases under a wide range of growing and environmental conditions . The classical approach has involved the use of multispectral data for the development of numerous vegetation indexes to measure biomass (e.g., Normalized Difference Vegetation Index, NDVI), water content (e.g., Water Band Index, WBI), or pigment composition (e.g., Modified Chlorophyll Absorption Ratio Index, MCARI) in yield studies. At present, the use of information derived from RGB images (using red, green, and blue color bands) acquired with conventional digital cameras represents a low-cost alternative. The images can be processed to convert RGB values into indexes based on the models of Hue-Intensity-Saturation (HIS), CIELab, and CIELuv cylindrical coordinate representations of colors . Moreover, recent technological advances have led the incorporation of these sensors into aerial based platforms, enabling the simultaneous characterization of specific crop physiological traits for a larger number of plots, which may help to minimize the effect of changing environmental conditions during critical sampling moments [18,21–24].
Available online 10 July 2008 Planting basins and ripper tillage practices are major components of the recently introduced conservationagriculture package that is being extensively promoted for smallholder farming in Zimbabwe. Besides pre- paring land for crop planting, these two technologies also help in collecting and using rainwater more effi- ciently in semi-aridareas. The basin tillage is being targeted for households with limited or no access to draught animals while ripping is meant for smallholder farmers with some draught animal power. Trials were established at four farms in Gwanda and Insiza in southern Zimbabwe to determine soil water contri- butions and runoff water losses from plots under four different tillage treatments. The tillage treatments were hand-dug planting basins, ripping, conventional spring and double ploughing using animal-drawn implements. The initial intention was to measure soil water changes and runoff losses from cropped plots under the four tillage practices. However, due to total crop failure, only soil water and runoff were mea- sured from bare plots between December 2006 and April 2007. Runoff losses were highest under conven- tional ploughing. Planting basins retained most of the rainwater that fell during each rainfall event. The amount of rainfall received at each farm significantly influenced the volume of runoff water measured. Runoff water volume increased with increase in the amount of rainfall received at each farm. Soil water content was consistently higher under basin tillage than the other three tillage treatments. Significant dif- ferences in soil water content were observed across the farms according to soil types from sand to loamy sand. The basin tillage method gives a better control of water losses from the farmers’ fields. The planting basin tillage method has a greater potential for providing soil water to crops than ripper, double and sin- gle conventional ploughing practices.
Generally, rainfall onset, cessation, distribution, and amount have considerable effect on maize yields and food security particularly under rain-fed conditions com- mon in lower eastern Kenya. Rainfall distribution and amount is of paramount importance to rain-fed agricul- ture prevalent in Kenya’s ASALs. The impact of this variability can be very momentous on crop yields espe- cially under rainfall agriculture in the ASALs [7, 16]. The results have shown that the less the rainfall variabil- ity, the less maizeyield anomalies thus the more reliable the rain is for maize production. The results appear to support the view of  that higher variations in rainfall above the mean eventually leads to fluctuations in maize yields and thus food insecurity. Within the ASALs which are more dependent on rain-fed agriculture variable rains, increasing temperatures and high evapotranspir- ation will adversely affect maize yields. As recently dem- onstrated  maize yields in Africa at lower altitudes is likely to fall by 20–50 % because of drying and warming as a result of climate change. In many places in lower eastern Kenya recent studies have indicated that there is an increased warming and potential evapotranspiration thereby worsening stress . In terms of adaptation op- tions at household level, it means that the farmers have to turn planting drought and heat tolerant crops.
Farmers in Machang’a identiﬁed high fertility ﬁelds as sections where they always planted maize while low fertility ﬁelds were iden- ti ﬁed as sections where they planted either cowpeas (Vigna unguiculata) or millet (Panicum miliaceum). In Kibugu, farmers di ﬀerentiated high and low fertility ﬁelds mainly by maize grain yield production history. After this di ﬀerentiation, the actual maize grain production from our control treatment was used to reclassify the farms using data from the ﬁrst season of grain production in each location. In Kibugu, the ﬁrst trial season (LR2017) grain production was used for the reclassiﬁcation, while in Machang ’a, the second trial season (SR2017) grain production was used since there was no grain production in LR2017. Control ﬁelds with a production of below 1 ton ha −1 were classiﬁed as low fertility ﬁelds. As majority of farmers in the study area practiced maize- monocropping, the trials tried to mimic their practice. In addition to this observation, Pittelkow et al. (2015) has highlighted the need to investigate the e ﬀects of no tillage in the tropical environments. The trials were then designed in support of these, i.e., test NTR and NTRM management systems on maize-monocropping. Studies have also shown that farmers from Africa tend to adopt one or two principles of CA as an entry point to full adoption ( Corbeels et al., 2014 ). In support of this, Thierfelder and Wall (2009) stated that “the principle of minimum soil disturbance is more adopted by farmers, the retention of crop residues as mulch and the introduction of crop rotations and associations is more complex”. Stepwise adoption of CA has also been reported, with farmers ﬁrst implementing reduced tillage followed by the introduction of 30 % residue retention ( Lahmar, 2010 ). For the purpose of this study, we deﬁne our management practices as follows; 1) a conventional control with no inputs which depicts farmers practice in the study lo- cations (C), 2) a CA-based treatment involving no tillage and residue retention (NTR), 3) an ISFM-based treatment involving conventional tillage and use of manure (CTM), and 4) a combination of the CA- and ISFM-based treatments involving no tillage, residue retention and use of manure (NTRM). Table 1 shows a summary of the management prac- tices as implemented. In each ﬁeld, the four treatments were laid down following a one farm one replicate randomized design. Per location, plots measured 10 by 5 m in two farms (mother farms) and 5 m by 3.5 m in eight farms (satellite farms). In the mother farms, SWC was mon- itored during the trial period and NUE was determined. It is important to note that rather than evaluating the individual components that constitute the tested treatments, such as tillage, residue retention, use of fertilizer and manure, the setup was designed to compare the alter- native cropping systems.
In each municipality, we identified main agricultural pro- duction zones with local extension service agents. After- wards, villages were randomly selected in these zones and the number of villages by municipality is proportional (11 to 12%) to the total number of villages that each munici- pality holds. Bassila holds 31 villages whereas Boukoumbé holds 71 villages . We surveyed four villages in Bassila (Adjiro, Aoro-Lokpa, Camp pionier and Mondogui) and eight villages in Boukoumbé (Dimatema, Dipokor 1, Ditch- endia, Koukongou, Kounadogou, Koutchata, Okouaro and Tassayota). Each surveyed village exhibit a dominant socio- linguistic group. A sociolinguistic group is understood here as a group in which a member inherits a common lan- guage of communication and shares social attributes such as customs, history, and food habits as recognized by Achigan-Dako et al. . We carried out a focus group discussion in each village with about 20 community mem- bers and with a balanced representation of men, women, and different age groups. The socially defined age classes (youth - an unmarried individual; an adult - an individual married, but not considered an elder; and elder ) were considered. Participants in focus group discussions are community’s members locally recognized as knowledgeable about edible plants. Those participants were invited by the chief of the village and their peers. We obtained a permis- sion of the chief of each village before conducting a focus group discussion, and followed the ethical guidelines of the International Society of Ethnobiology . Participants were asked to build a free and an agreed list of edible plants consumed in the villages and to indicate their status (e.g. cultivated, wild or under domestication), utilizations and plant parts used. For local people, a “cultivated” species is a crop plant that is only known to be cultivated in the village; a “wild” species referred to any other food plants ranging from truly wild (entirely wild and collected only when needed) to wild-protected (maintained and protected or preserved in fields and fallows or around habitats with a sort of ownership), and semi-domesticated plants (culti- vated in home gardens or in selected parts of cultivated
A BSTRACT : Acacias are spectacular angiosperms grouping single canopy species to those of tropical forests. Easy growth, hardiness and drought resistance of these Australian Wattle trees give them variable and great economic importance. Indeed, among other they produce, wood, edible seeds, gums and provide a valuable source of high quality fodder, rich in protein for subsistence and commercial production of livestock because they provide foliage during dry periods in the absence of herbaceous species. In addition, they contribute to the warmer climate of arid and semi-aridareas by reducing evaporation and creating a shadow that slows the soil drying and provide the setting and coastal sand dunes with their lateral root system that promotes better maintenance of the sand particles cohesion. Moreover, their ability to develop a dual symbiosis with Rhizobium bacteria and mycorrhizal fungi confers ecological importance. Indeed, they provide soil enrichment and improvement of soil fertility due to their ability to fix atmospheric nitrogen and to explore deep horizons of the soil by their roots. All these factors make it an economic resource of a great environmental and social importance, especially in arid and semi-aridareas, and an excellent candidate for reforestation of Mediterranean areas.
Agriculture remains vital for Africa as over 60% of African population depends on some form of farming for their nourishment and livelihoods (Diao et al., 2010). Indeed the sector is important for the continent‘s development and economic growth (Gollin, 2014). Therefore, efforts to reduce poverty in Africa must pay particular attention to the agricultural sector. In Rwanda, besides agriculture‘s contribution to GDP, the sector typically generates about 90% of employment (especially for women), about 70% of export revenues and about 90% of national food need (Cantore, 2011a). Attempts to increase agricultural production and food consumption are destabilized by rapid population growth (Boserup, 2005). Consequently, crop productivity is declining (Kelly et al., 2001; Cantore, 2011b) as a result of intensive farming, which leads to soil degradation through erosion and declining soil fertility (Kagabo et al., 2013). In 2007 Crop Intensification Program (CIP) policy in Rwanda was started with its aim to boost agricultural productivity through an improvement of productive inputs use, irrigation and rainwater use efficiency and soil quality (Cantore, 2011a). To date, however, expected potential increase in production has not been attained probably due to low soil fertility, low fertilizer response and rainfall variability.