Posts Tagged ‘Field Crops Research’

Mapping field-scale yield gaps for maize: An example from Bangladesh

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 143 : 151-156, 2013

U. Schulthess, J. Timsina, J.M. Herrera and A. McDonald

Accurate estimation of the size and spatial distribution of the yield gap has many practical applications, including relevance to precision agriculture and technology targeting. The objectives of this study were to illustrate a methodology to create a yield gap map and to discuss its potential uses to provide optimal crop management recommendations to the farmers. We used the HybridMaize crop simulation model to estimate potential yield for maize grown in the winter season in northwestern Bangladesh. This is a high yielding environment, where farmers achieve yields as high as 12 Mg/ha. The model predicted a mean potential yield of 12.87 Mg/ha. We used a RapidEye satellite image acquired around tasseling to identify the maize fields, calculate ground cover and its regression to actual yield from farmers’ fields. Next, the regression was applied to all the maize pixels in the image to calculate actual yield. In the last step, we created a yield gap map based on the difference between potential and actual yield. Yield gap maps will enable agronomists to identify production constraints on farmers’ fields with large yield gaps. Alternatively, by learning from the farmers with the highest actual yields and analyzing their data, it will be possible to generate region or field specific, optimized crop management recommendations.

 

 

Maize-based conservation agriculture systems in Malawi: Long-term trends in productivity

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 142 : 47-57, 2013

Christian Thierfelder, John L. Chisui, Mphatso Gama, Stephanie Cheesman, Zwide D. Jere, W. Trent Bunderson, Neal S. Eash and Leonard Rusinamhodzi

In Malawi and throughout much of Africa, maize yields have declined over the past several decades due to continuous cultivation, often in monocropping with little or no inputs. As a result, soil degradation has been aggravated by the loss of valuable top soil caused by rainwater runoff due to the absence of effective conservation practices. To combat this trend, Conservation Agriculture (CA) systems were introduced using a pointed stick or hand hoe to plant directly into untilled soil with crop residues as surface mulch. The objective of this study was to compare the effects of different cropping systems (CA and conventional) on soil physical and chemical parameters and long-term maize productivity in target communities of the southern and central regions of Malawi. This study analysed the effects of CA on soil parameters and maize yield over eight cropping seasons. The biophysical variability of the communities was explored through principal component analysis. Results showed that maize yields in CA systems were strongly affected by rainfall infiltration, which was 24–40% greater compared with the conventional ridge and furrow system. In some cases, maize yields in CA plots were double that of conventional tillage plots. The larger water infiltration observed in CA plots relative to conventional tillage indicated that CA systems may increase access to soil water by the crop and offset the negative effects of seasonal dry spells. Yield benefits of CA over conventional tillage systems were greater especially from the 5th season although, in some instances, greater yields on CA were recorded almost immediately. CA can be practiced in diverse environments from sandy to clay soils, nutrient rich to infertile soils and from low to high rainfall areas as long as adequate inputs (fertilizer, herbicides and labour) are available with good extension support to farmers, especially in the initial years.

Genetic variability of tropical maize stover quality and the potential for genetic improvement of food-feed value in India

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research, 2012

 P.H. Zaidi, M.T. Vinayan and M. Blummel

 Sixty elite maize inbred lines were selected from CIMMYT-Asia maize program for stover fodder quality analysis. These lines were selected based on high per se and cross performance across several locations in the Asian tropics and have wide adaptability across the region. The line evaluation trials were conducted using recommended agronomic practices during the off-season of 2009 at ICRISAT farm in Hyderabad, India. Data were recorded on various agronomic traits including yields. At harvest the stover was analyzed for a range of fodder quality traits. On the basis of high stover in vitro digestibility (IVOMD) (a trait chosen because it correlated well with pricing in fodder trading of another coarse stover, namely sorghum) and high grain yield, the top ranking 10 inbred lines were selected and crossed in all possible combinations (excluding reciprocals) using diallel mating design in the rainy season of 2010. A total of 26 crosses along with four commercial hybrid checks were selected and planted in two replicates for evaluation during the dry season of 2010.

A wide range in performance was observed in grain and stover traits. Grain and stover yields ranged from 0.94 to 7.3 t/ha (P < 0.0001) and from 2.0 to 8.5 t/ha (P < 0.0001), respectively. Stover IVOMD ranged from 46.9 to 55.5% (P = 0.08). Grain and stover traits showed a considerable degree of independency. Grain and stover yield were significantly positively correlated (r = 0.53; P = 0.003), however, grain yields at around 7.0 t/ha showed varied stover yields ranges from 3.5 to 6 t/ha. No significant correlation was observed between IVOMD and grain yield (r = −0.12, P = 0.52) or IVOMD and stover yield (r = 0.03; P = 0.98). It is striking that the cross with the third highest grain yield (7.1 t/ha) had the second highest stover digestibility (about 55%).

Effect of different tillage and seeding methods on energy use efficiency and productivity of wheat in the Indo-Gangetic plains

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 142 : 1-8, 2012

Vivak Kumar, Yashpal S. Saharawat,  Mahesh K. Gathala, Arjun Singh Jat, Sanjay K. Singh, Neelam Chaudhary and M.L. Jat

Conservation agriculture (CA) based crop management technologies specially zero- or minimum-tillage are being rapidly adopted by the farmers in intensively cultivated wheat (Triticum aestivum L.) production systems of South Asia. Farmers use these tillage options considering them best as per their wisdom. However, scanty information is available on relative energy and economic efficacy of different tillage and seeding implements being used by the farmers for wheat production in the Indo-Gangetic Plains (IGP) of South Asia. We investigated the effect of five wheat establishment methods (i) conventional tillage; (ii) reduced-tillage; (iii) rotavator tillage; (iv) raised bed planting; and (v) zero-tillage for their energy and economic efficiency in a Typic Ustochrept alluvial sandy loam soil in the IGP during 2005–2008. We hypothesized that (1) zero- or minimum-tillage implements would lead to improved operational field capacity; (2) the CA based technologies would enhance energy efficiency; and (3) overall these tillage and seeding methods would enhance net income and crop productivity. We measured implement efficiency, energy inputs and outputs, tillage and seeding efficiency as well as wheat productivity and economics. The results of the study showed that zero-tillage improved the operational field capacity by 81%, specific energy by 17% and the energy usage efficiency by 13% as compared to the conventional tillage. But, higher total effective field capacity (9.93 h ha−1) on raised beds is in contrast with our second hypothesis. The enhanced net income in zero-tillage (33%) and reduced-tillage (20%) compared to CT support the third hypothesis. The overall results of the study revealed that CA-based crop establishment practices are a viable options for the farmers not only in terms of energy and time efficiency but also for attaining higher productivity and profitability. There exists a large potential of CA based crop establishment practices in South Asia not only in terms of crop productivity and profitability but also their energy efficiency, global warming potential and soil health. The study also emphasizes for long-term strategic research in systems perspective for better understanding CA based technologies in different efficiency and soil health aspects.

 

Performance of biofortified spring wheat genotypes in target environments for grain zinc and iron concentrations

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 137 : 261-267, 2012

G. Velu, R.P. Singh, J. Huerta-Espino, R.J. Peña, B. Arun, A. Mahendru-Singh, M. Yaqub Mujahid, V.S. Sohu, G.S. Mavi, J. Crossa, G. Alvarado, A.K. Joshi and W.H. Pfeiffer

Genetic biofortification to improve zinc (Zn) and iron (Fe) concentrations in bread wheat (Triticum aestivum L.) could reduce micronutrient malnutrition-related problems in the developing world. A breeding program on wheat was started to enhance Zn and Fe concentrations and other essential traits needed in a successful commercial variety. The first set of advanced lines derived from crosses of high yielding wheats with genetic resources possessing high Zn and Fe such as Triticum spelta, landraces and synthetic wheat based on Triticum dicoccon were tested at nine locations in South Asia and Mexico for Zn and Fe concentration, grain yield and other traits. Analyses of variance across locations revealed significant genotypic, environmental and genotype × environment (G × E) effects for grain Zn and Fe concentrations and grain yield. Variances associated with environmental effects were larger than the genotypic and G × E effects for all three traits, suggesting that environmental effects have relatively greater influence. Although G × E interaction was significant, high heritabilities were observed for Zn and Fe concentrations at individual sites and across environments, reflecting non-crossover type of interaction. This trend was confirmed by the high genetic correlations between locations that showed similar ranking of entries across locations, indicating that it is possible to select the best adapted entries with high Zn and Fe concentration. Pooled data across locations showed increments of 28% and 25% over the checks for Zn and Fe. A considerable number of entries exceeded intermediate to full breeding target Zn concentrations, indicating that it is possible to develop Zn-biofortified varieties with competitive yields and other farmer preferred agronomic traits. The positive and moderately high correlation between Zn and Fe concentration suggest good prospects of simultaneous improvement for both micronutrients.

A comparative analysis of conservation agriculture systems: Benefits and challenges of rotations and intercropping in Zimbabwe

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 137 : 237-250, 2012

Christian Thierfelder,  Stephanie Cheesman and Leonard Rusinamhodzi

Increasing soil degradation in southern Africa and the potentially negative effects of climate change demand “greener” solutions to reverse this trend. Conservation agriculture (CA) has been proposed as one of those solutions and field level data show marked benefits of this new cropping system. Nevertheless, the use of rotations and/or associations in CA systems is challenging at both the farm and community level. Intercropped maize (Zea mays L.) with grain legumes, cowpea and pigeonpea (Cajanus cajan L. (Millsp.)), as well as maize rotated with cowpea (Vigna unguiculata L. (Walp)) and sunnhemp (Crotalaria ochroleuca L.) was studied for up to eight seasons under CA and conventional agriculture in Zimbabwe. The objective of this study, carried out on-farm and on-station, was to highlight the effects of CA systems on some soil quality indicators and crop productivity. Where possible the specific effects of rotation and intercropping was separated and compared with monocropping. The on-station and on-farm results show: an increase of up to 331% in water infiltration, a 31% greater soil carbon in the top 60 cm than on adjacent conventionally ploughed fields, a 6% lower bulk density in the top 10 cm and 32.5–36 t ha−1 less cumulative soil erosion in CA fields after seven cropping seasons compared with the conventional control treatment. The comparative productivity analysis between continuous maize, maize intercropped with cowpea or pigeonpea and maize in rotation with cowpea or sunnhemp, shows marked benefits of rotation especially in CA systems. The benefits of CA especially when rotated with leguminous crops, increase over time, suggesting that there are improvements in soil structure and fertility. However, field level benefits will not increase the overall adoption of rotations and intercropping in CA systems, unless the socio-economic constraints at the farm and community level are addressed.

Exploring the possibility of obtaining terminal heat tolerance in a doubled haploid population of spring wheat (Triticum aestivum L.) in the eastern Gangetic plains of India

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 135: 1-9, 2012

Chhavi Tiwari, Hugh Wallwork, Ram Dhari, B. Arun, V.K. Mishra and Arun K. Joshi

High temperature during grain filling stage causes significant yield losses to wheat in south Asia and many other parts of the world. One hundred and forty doubled haploid (DH) wheat lines (including parents), derived from the cross Berkut (heat susceptible) × Krichauff (heat tolerant), were grown in six environments comprising two dates of sowing in three consecutive years (2007–2008, 2008–2009, and 2009–2010) at Banaras Hindu University, Varanasi, India. The objective was to assess DH lines for heat tolerance and to identify superior lines under hot humid environments of the eastern Gangetic plains (EGP) of India. Considerable variation was observed for grain yield (GY), thousand grain weight (TGW), grain fill duration (GFD), and canopy temperature (CT). Likewise, considerable variation was also observed for heat susceptibility index (HSI) of GY, TGW, and GFD. The DH lines were grouped into four categories based on the HSI and around 5–10% lines were categorized as heat tolerant. A few lines yielded significantly more than the better parent and possessed good expression of other traits. The most promising 20 lines have been listed as sources of heat tolerance, with 3 lines better yielding than the superior parent Krichauff. The results demonstrated that it is possible to obtain lines that perform better for yield and yield related traits in heat stressed environments of the EGP of India.

Medium-term effects of conservation agriculture based cropping systems for sustainable soil and water management and crop productivity in the Ethiopian highlands

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 132 (1): 53-62, 2012

Tesfay Araya, Wim M. Cornelis, Jan Nyssen, Bram Govaerts, Fekadu Getnet, Hans Bauer, Kassa Amare, Dirk Raes, Mitiku Haile, Jozef Deckers

In the northern Ethiopian highlands, croplands yield extremely high volumes of storm runoff and are the major contributor to sediment load in the rivers. A medium-term tillage experiment was carried out (2005–2010) on a Vertisol to quantify changes in runoff, soil loss and crop yield due to Conservation agriculture (CA) in the sub-humid May Zegzeg catchment. A randomized complete block design with 3 replications on permanent plots of 5 m by 14 m was used for three tillage treatments, (i) derdero+ (DER+), permanent raised beds with 30% standing crop residue retention and no-tillage on the top of the bed, (ii) terwah+ (TER+), ploughed once at sowing with 30% standing crop residue retention and furrows made at 1.5 m interval, and (iii) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues. Tillage operations in the three treatments were done using the local ard plough mahresha. Local crop rotation practices followed during the six years sequentially from the first to the sixth year included wheat-grass pea-wheat-hanfets (wheat and barley sown together)-grass pea-wheat. Glyphosate was sprayed starting from the third year (2007) at 2 L/ha before planting to control pre-emergent weed in DER+ and TER+. Runoff and soil loss were measured in collector trenches at the lower end of each plot. Soil organic matter was determined at two depths (0–15 cm) and (15–30 cm). Local farmers evaluated crop stands. Significantly different (p < 0.05) 4-yr mean soil losses of 14, 17 and 26 t/ha, 5-yr mean runoff depth of 76, 95 and 118 mm, and 5-yr runoff coefficient of 19, 24 and 30% were recorded for DER+, TER+ and CT, respectively. Soil organic matter was significantly higher in DER+ and TER+ compared to CT. The mean farmers’ evaluation of crop performance in the last three years (2008–2010) showed a significant higher score for DER+ (6/8) followed by TER+ (5.6) and least for CT (4.8/8), and improvements in crop yield were observed; however, a period of at least five years of cropping was required before the difference became significant. In addition to the positive effects on runoff, soil loss and crop yield, we argue that avoiding repeated tillage which is 10–11 oxen-span days per ha and the faster ploughing pace at sowing in DER+ will enable a reduction in oxen density with further natural resource benefits. DER + and TER+ are improvements to good local practices that qualify them as CA: we recommend large scale dissemination and implementation on Vertisols.


 

Striga hermonthica parasitism in maize in response to N and P fertilisers

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 134 (12): 1-10, 2012

M. Jamil, F.K. Kanampiu, H. Karaya, T. Charnikhova, H.J. Bouwmeester

Parasitism by the parasitic weed, Striga hermonthica (Striga), constitutes a major biological constraint to maize production in sub-Sahara Africa. Nutrient deficiency is known to aggravate Striga infestation and in a number of plant species it was recently shown that this may be due to increased secretion of Strigagermination stimulants into the soil. The present study was designed to observe the connection between soil fertility, secretion of germination stimulants and Striga infection in maize under greenhouse and field conditions. The experiments were conducted during two successive cropping seasons (2008 and 2009). The greenhouse study showed that maize secretes a number of so far unidentified strigolactones that induceStriga seed germination and the amount of these strigolactones increases upon N and P deficiency. The increased secretion of germination stimulants under N and P deficiency resulted in increased Striga infection in pot experiments. The on-station and on-farm field trials in Western Kenya also showed reduction in Strigainfestation with the application of mineral nutrients but the results were less consistent than in the greenhouse. Increasing levels of N showed a fair reduction of Striga in the field especially during the first year, whereas P application did not have much effect in contrast to the greenhouse study where both N and P clearly reduced Striga infection. The likely explanation for this discrepancy is that availability of mineral nutrients under field conditions is less predictable than under greenhouse conditions, due to a number of factors such as soil texture and structure, pH, salinity, drought, leaching and runoff. Hence, further studies are needed on the importance of these factors before a fertiliser application strategy can be formulated to improve control of Striga in maize in the field.

Conservation Agriculture in mixed crop–livestock systems: Scoping crop residue trade-offs in Sub-Saharan Africa and South Asia

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research  132 : 175-184, 2012

Diego Valbuena, Olaf Erenstein, Sabine Homann-Kee Tui, Tahirou Abdoulaye, Lieven Claessens, Alan J. Duncan, Bruno Gerard,  Mariana C. Rufino, Nils Teufel, André van Rooyen, Mark T. van Wijk

Conservation Agriculture (CA) is being advocated to enhance soil health and sustain long term crop productivity in the developing world. One of CA’s key principles is the maintenance of soil cover often by retaining a proportion of crop residues on the field as mulch. Yet smallholder crop–livestock systems across Africa and Asia face trade-offs among various options for crop residue use. Knowledge of the potential trade-offs of leaving more residues as mulch is only partial and the objective of this research is to address some of these knowledge gaps by assessing the trade-offs in contrasting settings with mixed crop–livestock systems. The paper draws from village surveys in 12 sites in 9 different countries across Sub-Sahara Africa and South Asia. Sites were clustered into 3 groups along the combined population and livestock density gradients to assess current crop residue management practices and explore potential challenges to adopting mulching practices in different circumstances. Results show that although high-density sites face higher potential pressure on resources on an area basis, biomass production tends to be more substantial in these sites covering demands for livestock feed and allowing part of the residues to be used as mulch. In medium-density sites, although population and livestock densities are relatively lower, biomass is scarce and pressure on land and feed are high, increasing the pressure on crop residues and their opportunity cost as mulch. In low-density areas, population and livestock densities are relatively low and communal feed and fuel resources exist, resulting in lower potential pressure on residues on an area basis. Yet, biomass production is low and farmers largely rely on crop residues to feed livestock during the long dry season, implying substantial opportunity costs to their use as mulch. Despite its potential benefit for smallholder farmers across the density gradient, the introduction of CA-based mulching practices appears potentially easier in sites where biomass production is high enough to fulfil existing demands for feed and fuel. In sites with relatively high feed and fuel pressure, the eventual introduction of CA needs complementary research and development efforts to increase biomass production and/or develop alternative sources to alleviate the opportunity costs of leaving some crop residues as mulch.