Experiments in Brazil have shown that a sorghum-pulse (cowpea or common bean) intercrop system yielded more grain than the monocrop system and produced a Land Equivalent Ratio (LER) greater than 1.00 even though rainfall was limited. Sorghum competed less than maize with the associated pulse when Competitive Ratios (CR) were considered. In cowpeas, CR values were correlated positively with the number of pods and seeds plant−1. The two crops in the intercrop systems were responsive to fertilizer application. Thus, improved management (i.e. fertilizer usage) was appropriate without the loss of the advantageous effects realized from intercropping.

Climbing beans play a central role in food security of rural households in the densely populated highlands of East and Central Africa. Soil fertility degradation and the lack of nutrient inputs are major limitations to yield of beans and other crops. We conducted field trials in Northern Rwanda in Kinoni and Muko villages to evaluate the effect of mineral N, P, and K fertilizers (both alone and in combination) and farmyard manure on nitrogen fixation and grain yields of climbing bean in smallholder farmers’ fields. The trials were laid down in a randomized complete block design with seven replicate blocks in each village. Manure and fertilizer application led to greater yields in all fields, and the largest yields were achieved when manure was combined with NPK. Large variability in yield between fields was observed. Application of fertilizer together with manure increased the grain yield from 1.5 to 3.9 t ha−1 in Kinoni and from 2.6 to 5.4 t ha−1 in Muko. Fertilizer and/or manure increased stover yield from 0.8 to 2.3 t ha−1 in Kinoni and from 1.5 to 3.4 t ha−1 in Muko. Application of 30 kg P ha−1 and 5 t manure ha−1 led to increased N and P uptake (from 49 to 106 kg N ha−1 and from 6.1 to 12.4 kg P ha−1 in Kinoni and from 46 to 128 kg N ha−1 and from 5.3 to 17.9 kg P ha−1 in Muko). There was no clear relationship between soil fertility characteristics and the response of climbing bean to applied inputs at Muko site. However, at Kinoni site, limited response to manure and NPK application was observed in plots where soil available P and soil exchangeable K were relatively low. Our results show the benefits of using manure along with mineral fertilizers for increased climbing bean yields and nutrient uptake in smallholder farming systems.

Using computer simulation model as a management tool requires model calibration and validation against field data. A three-year (2008–2009 to 2010–2011) field study was conducted at the Postgraduate Agricultural Research Station of the University of Agriculture, Faisalabad, Pakistan, to simulate wheat grain yield production as a function of urea fertilizer applications using Crop Environment REsource Synthesis (CERES)-Wheat model. The model was calibrated using yield data for treatment of urea fertilizer application at the rate of 247 kg-urea ha−1 during growing season 2009–2010 and was validated against independent data sets of yield of two years (2008–2009 and 2010–2011) for a wide variety of treatments ranging from no urea application to 247 kg-urea ha−1 application. The model simulations were found to be acceptable for calibration as well as validation period, as the model evaluation indicators showed a mean difference of 8.9%, ranging from 0.05 to 15.38%, root mean square error of 356 having its range from 242 to 471 kg ha−1, against all observed grain yield data. The scenario simulations showed maximum grain yield of 4100 kg ha−1 for 350 kg-urea ha−1 in 2008–2009; 4600 kg ha−1 for 300 kg-urea ha−1 in 2009–2010 and 5200 kg ha−1 for 340 kg-urea ha−1 in 2010–2011. Any further increase in urea application resulted in decline of grain yield function. These results show that model has the ability to simulate effects of urea fertilizer applications on wheat yield; however, the simulated maximum grain yield data need field-based verification.

The apparent success of overdrilling in improving poor grazing pasture in other temperate climates led to an investigation of the technique under British conditions. With the development of a suitable machine, both for controlling competition and for drilling seeds and fertilizers simultaneously into established pasture, field trials were initiated in 1961 and 1962. Despite the achievement of satisfactory furrows for germination, the subsequent emergence and establishment of improved grasses and white clover was poor. This was thought to be due to various factors, particularly to competition from the short vigorous lowland swards, but also to unsatisfactory furrow environments where difficulties were experienced in covering seeds adequately, and in protecting seedlings from desiccation. Even when an overall application of herbicide was used to control competition, the seedlings were slow to colonize the bare ground and appeared to be particularly vulnerable to desiccation where vegetation was absent. Under the conditions of sward and climate at Aberystwyth, overdrilling by itself appears to offer no promise as a means of grassland improvement.

Maize (Zea mays L.) grain yield is severely constrained by drought and this study was conducted to assess gains in grain yield and other traits of released maize cultivars. Twenty-three maize cultivars plus a check were evaluated under drought and well-watered conditions at Zaria and Kadawa during 2015/2016 and 2016/2017 dry seasons. The 24 cultivars were evaluated using 6 x 4 lattice design with three replications. Genotypes differed significantly for all measured traits except anthesis-silking interval (ASI), husk cover, and number of ears per plant under drought, and ASI, husk cover, and ear aspect under well-watered conditions. Under drought, grain yield ranged from 2251 kg ha−1 for SAMMAZ 31 to 4938 kg ha−1 for SAMMAZ 19, with a genetic gain of 1.93% yr−1. Under well-watered conditions, grain yield varied from 3082 kg ha−1 for SAMMAZ 37 to 5689 kg ha−1 for SAMMAZ 51, with the same genetic gain found under drought conditions. Grain yield reduction as a result of drought was 28.4% and performance under drought predicted performance under well-watered conditions better than vice versa with regression coefficient value of 0.8. Grain yield had significant correlations with all measured traits under both water conditions, except for husk cover, plant and ear heights under drought. Our data revealed that substantial genetic gains have been made in breeding for high grain yield cultivars under drought and well-watered conditions over a period of 16 years in Nigeria.

This paper investigates the determinants of the performance of family farms in Senegal using both production and profit functions. The econometric analysis is based on agricultural inputs and outputs information from a survey of 504 agricultural households, member of a farmer organization in the Saint Louis region in 2009. Our main results indicate that the size of the cultivated plots has a negative effect on crop yields, representing diseconomies of scale. This finding suggests potential for improvements in farm management and organization. We also find that the development of commercialization sectors and loans could boost agricultural inputs. In terms of profitability, our results show that yields and prices play significant and important roles for all crops. An increase in the bargaining power of farmers would be required to increase unit prices and consequently their profits.

In experiments conducted with three rice varieties at different plant populations and N levels, the non-lodging varieties responded to 150 kg N/ha. The highest yield in non-lodging varieties were at the highest transplanted density, but at the lowest density in the lodging variety. The percentage of total milled rice of all varieties was not significantly affected by N application, which improved head-rice recovery in chalky IR-8, but had no significant effect on non-chalky varieties. Competition for nutrients could be a major factor limiting head rice return at high densities.

Judicious management of our natural resources is a major pillar of sustainable agriculture, broadly defined. It is, therefore, unfortunate that, until now, research in natural resources management (NRM) has not received sufficient support, or the recognition that other agricultural research topics have had. The Consultative Group on International Agricultural Research (CGIAR) recognized, early on, the complementarities and synergies between NRM research and other themes, notably genetic improvement, and its research Centres have pursued some vigorous programmes for many years. The Technical Advisory Committee (TAC) to the CGIAR was supportive of such programmes from the start and provided advice to the CGIAR System on NRM research strategies. Highlights of such advice over the last 20 years are discussed, including the ecoregional approach, the 1996 study of Priorities and Strategies for Soil and Water Research, and the CGIAR Vision and Strategy of 2000. Recent developments at the Centres leading to the promotion of integrated approaches to NRM (INRM) are described, and a set of priority areas in INRM research for future CGIAR activities is presented.

Pre-flowering insect infestation of cowpea, Vigna unguiculata, was monitored in weedy and weed-free plots in 1986 and 1987 in Akure, Nigeria. Weediness generally reduced infestations of both the leafhopper, Empoasca dolichi, and the flea beatle, Ootheca mutabilis. However, seed yield was reduced in the weedy plots despite heavier pre-flowering insect populations in the plots kept weed-free.

The effects of nitrogen fertilization on growth, nutrient uptake and yields of upland and lowland taro were studied on the island of Kauai, applying o, 280, 560 and 1120 kg./ha. N. Nitrogen concentrations of upland and lowland taro leaves were significantly correlated with yields, although regression analysis showed that per cent N in both blades and petioles decreased with age. Higher yields were obtained from the lowland than from the upland crop, regardless of amounts of N fertilizer applied. The highest yield obtained from lowland taro was at 1120 kg./ha. N harvested at fifteen months (57·6 tons/ha.) and from upland taro the highest yield was obtained at 560 kg./ha. N harvested also at fifteen months (25·5 tons/ha.).

Under rainfed conditions in Tarlac, Central Luzon, Philippines, risk was characterized using field and household panel data for 46 rice farmers over the period 1990–93. Measures of risk at the field level were calculated using pooled time-series cross-sectional data. Field-level risk was found to be quite high, with the average coefficient of variation of yield being 45% and 30% for fields with low and moderate elevations respectively. Farmers applied less nitrogen in fields with higher yield variability, and adjusted the quantity of nitrogen in order to reduce losses in poor years and benefit from greater potential in good years. Farmers with higher levels of education had lower variability of rice income than farmers with a lower level of education. Non-crop income helped reduce total income variability, especially for farmers with high variability of crop income. Implications for technology design and policy improvements are derived from these results.

In 1981 and 1982, three crop protection regimes were compared with an unsprayed control for cowpea grown alone and in mixtures with maize, sorghum and cotton. Unsprayed cowpea in mixtures with maize had yields which suggested some pest escape in 1981 but not in 1982. When sprayed, only the maize–cowpea mixture showed much yield advantage over sole crops. For maize–cowpea in 1983, a very dry year, only the alternate row mixtures showed a yield advantage and three spray applications gave cowpea yields as good as those resulting from six applications. The late, photosensitive cowpea variety Acq 1696 had better yields than the medium maturity TVx1948·01 F in the mixed crop but was greatly inferior as a sole crop.

Topsoil depth and yields of sorghum, pearl millet and castor bean were found to be positively correlated when monitored over thirteen seasons under widely varying rainfall conditions on an Alfisol in Andhra Pradesh, India. Yields responded up to 2.5 times more to topsoil depth when rainfall in the critical period exceeded evapotranspiration than under drier conditions. Yield variations were explained by topsoil depth in cereals, and by the interaction between rainfall during the critical period and topsoil depth in cereals and castor bean (R2<0.72). The expected yield losses as a result of erosion, based on 56 years of rainfall data, were 138, 84 and 51 kg ha−1 cm−1 for sorghum, pearl millet and castor bean, respectively. Quadratic models explained the yield losses due to cumulative erosion under conditions of both poor and good rainfall during the critical period. Sorghum and pearl millet tended to produce no yield when erosion exceeded 34 cm and castor bean when it exceeded 40 cm. There was less reduction in yield when rainfall was poor, up to about 10 cm of erosion, than when rainfall was good. The results indicate that pearl millet and castor bean are more suitable than sorghum for low rainfall and eroded conditions.

Dormancy in seeds of Sesbania sesban is caused by a water-impermeable seed coat (hard seeds or hardseededness). A two-phase pretreatment technique was developed for breaking seed dormancy and was validated using different accessions and seed lots. Seeds were first soaked in water at 80 °C for 8 min and prepared for the germination test. Ungerminated hard seeds at the first count (after four days incubation) during the germination test were then subjected to a second treatment by mechanically scarifying the seed coat. The effects of water temperature and variation in initial hardseededness and viability among and within accessions were also investigated. The optimum water temperature, allowing maximum seed germination without increasing the percentage of abnormal seedling/dead seeds was 80 °C. The mean percentage of hard seeds across 30 seed lots of six accessions was reduced to 26% after phase 1 and to 0% after phase 2. In addition, full germination occurred within only 10 days for treated seeds while germination in untreated seeds had reached only 48% after 14 days. Significant differences existed among the seed lots within the accessions (p > 0.05) for the percentage of initial hard seed and for the effects of treatments on breaking seed dormancy. The two-phase technique developed was validated using over 1000 seed lots of S. sesban, and it was found to be a rapid and cost-effective method for breaking hard seed dormancy with potential for wider use for hard-seeded legumes.

The impact of liquid cattle (Bos taurus L.) manure, applied to soil at common rates and for several years, on certain plant parameters and soil properties has not been studied extensively. The objectives of this study were: a) to assess the effects of manure application on corn (Zea mays L.) yield, macro- and micronutrient concentrations and uptake, in a three-year (2006–2008) field experiment conducted in northern Greece and b) to evaluate the 11-year effect of manure application on soil fertility (particularly on micronutrients avialability) and chemical properties (especially on organic C and total N content). The field experiment of this study had been used in a similar fertilisation experiment since 1996. The treatments, which were applied on the same plots each year over the 11-year period, were: (i) soil incorporation of liquid dairy cattle manure before sowing, at a rate equal to the common N-P inorganic fertilisation for each crop (based on manure's total N and P content); (ii) application of the common inorganic N-P fertilisation for each crop before sowing; (iii) identical to ii, but with split application of the N fertilisers; (iv) no fertilisation (control). Corn dry aboveground biomass yield at the R3 growth stage and grain yield, N, P, K concentrations and macro- and micronutrients uptake increased (p ≤ 0.05) upon manure addition at levels similar to or higher than the inorganic fertilisation treatments. The relative increase in grain yield during the three-year period ranged between 63–75% for manure treatment and 50–75% for both inorganic fertilisation treatments. After 11 years of manure application, organic C, total N, and available NO3-N, P, K, Cu, Zn, Mn, and B increased (p ≤ 0.05) in the surface soil (0–30 cm). However, no trend of nutrient build up was evident through years (except for Zn). Surprisingly, salinity and available NO3-N in the 60–90 cm soil depth of the manure-treated plots were lower (p ≤ 0.05) than that of the inorganic fertilisation treatments and similar to control. Electrical conductivity was 1.76, 3.05, 2.96 and 1.36 dS m−1, for manure treatment, the two inorganic fertilisation treatments and control, respectively, whereas the respective NO3-N concentrations were 7.7, 44.6, 55.1 and 8.3 mg kg−1. Conclusively, repeated application of liquid cattle manure into the soil, at rates comparable to the common inorganic fertilisation for 11 years, can enhance crop yield and macronutrient concentrations in plant tissues and uptake, at levels similar to the inorganic fertilisation. In addition, it can increase micronutrients plant uptake and maintain soil fertility with respect to both macro- and micronutrients and increase soil organic C and total N, without either causing nutrient build up or increasing soil salinity and NO3− accumulation in the deeper soil layers.

The pattern of yield and productivity of a typical Raphia swamp is described and suggestions are made for improving the crop by selection

The nature of the soil, the influence of previous natural grassland, ley, fallow or cultivation, and the weather conditions before and after planting are shown to affect the yield of wheat, and its response to fertilizers, especially nitrogen. Out of seventeen experiments over four seasons, involving nitrogen top-dressings on wheat, thirteen gave economic increases after the application of I cwt per acre of ammonium sulphate nitrate (A.S.N.). Such applications to the first, second or third wheat crops after Rhodes grass (Chloris gayana) ley, or to land continuously cropped for a number of years, nearly always gave an economic increase in grain yield, but on continuously cultivated land, with normal rainfall after planting, an economic return to a second cwt per acre was probable. Following a one-season fallow, economic responses to nitrogen only occurred when the pre-planting period was very wet. Yields of wheat after ley, both with and without applied nitrogen, tended to be superior to those on continuously-cropped land. Responses to phosphorus only occurred in one area, where the importance of applying both N and P, particularly to newly-ploughed grassland, was very evident. Loss of organic matter, and structural deterioration accompanied by lower efficiency in the utilization of water and nitrogen, are probably the main causes of falling yields on soils cultivated for many years. The use of grass/legume leys is suggested as the best means of maintaining these naturally fertile soils in a highly productive state, even though the present returns from the legs themselves may be less profitable than wheat cropping.

Legumes have gained increased importance in smallholder farming systems of sub-Saharan Africa due to their contribution to household nutrition and health and their ability to grow in low fertility soils. With unpredictable and highly variable rainfall characteristics of the semi-arid areas, short-season grain types are seen as a promising option for drought avoidance. Knowledge of phenological development and, in particular, time to flowering is crucial information needed for estimating the possible production success of new accessions to new environments. The photoperiod-sensitivity of 10 promising short-season Lablab purpureus (L.) Sweet accessions (CPI 525313, CPI 52533, CPI 52535, CPI 52535, CPI 52552, CPI 52554, CPI 60795, CPI 81364, CQ 3620, Q 6880B) were evaluated for their response to varying temperature and daylength regimes in field trials in Limpopo province, South Africa and under controlled conditions in growth chamber experiments in Göttingen, Germany. Photoperiod sensitivity was quantified using the triple-plane rate model of flowering response with time to flowering expressed in thermal time (Tt, °Cd). Additionally, piecewise regression analysis was conducted to estimate the critical photoperiod (Pc) above which time to flowering was delayed significantly. Relatively high variation of time to flowering amongst and within accessions in days after planting (DAP) was observed, ranging from 60 to 120 DAP depending on sowing date or daylength/temperature regime. Furthermore, a clear positive effect of temperature on growth and development of the tested accessions was found and time to flowering expressed as thermal time were consistent for the tested accessions, ranging from 600 to 800 °Cd for daylength <13 h. Only at daylength of ≥13 h and temperatures above 28 °C, development towards flowering was delayed significantly for accessions CPI 52513, CPI 52535, CPI 52554 and CPI 60795 with vegetative growth continuing for >110 DAP. The tested lablab accessions are therefore considered photoperiod insensitive, or weakly photoperiod responsive and are classified as short-day plants (SDP). Since daylength does not exceed 13 h between the latitudes 30 N to 30 S, these lablab accessions are recommended for further testing as short-duration grain legumes.

The effect of seven planting densities on yield and witches' broom disease incidence in hybrid cacao (Theobroma cacao) trees in the Brazilian Amazon was investigated. Data collected over a three-year period showed that it was possible to optimize regional cacao yield by high planting densities (2500 and 1666 trees ha−1) and that there was no density × year interaction. However, high planting density also favoured witches' broom incidence. A growing regional interest in planting cacao clones at high planting density should be pursued with caution, since high planting densities of clones in environments under strong pressure of selection for the witches' broom pathogen, such as in the Amazon region, are still a risky strategy. Alternatives to the high planting density system are presented and discussed.