A total of 36 root‑nodule bacteria were isolated from southern Ethiopia using the Red Wolaita common bean variety, and 26 were authenticated as rhizobia and then screened for symbiotic effectiveness in a greenhouse at Arba Minch University. Among the authentic isolates, strains AMU23, AMU74, and AMU3A had symbiotic effectiveness values of 138%, 117%, and 116.7%, respectively, and were further evaluated along with a commercial strain, HB429, in farmers’ fields at varying altitudes with the Red Wolaita common bean variety. The selected rhizobial isolates were introduced by seed inoculation with coal‑based formulations prepared under controlled laboratory conditions, along with a commercial reference inoculant. In the field trial, the native strain AMU23 showed the highest nodule number (138.3), nitrogen derived from the atmosphere (84%), and grain yield (2.24 tons ha⁻¹), with superior production‑induced traits and larger effects at the lower altitude (Arguba site, 1160 m.a.s.l.). On the other hand, the strain AMU74 had the highest performance at the higher altitude (Tegecha site, 2174 m.a.s.l.), suggesting that native strains’ symbiotic efficiency and yield improvement were influenced by altitude. However, their effectiveness was also influenced by soil fertility parameters and environmental factors. In comparison, the commercial strain exhibited significantly lower grain yield and symbiotic performance (p < 0.05) than the native strains at both locations, yet it still improved productivity, indicating the superior efficacy of the locally sourced strains over the commercial inoculant. A multi‑locus sequence analysis (MLSA) clustered the native strains within the Rhizobium etli–Rhizobium phaseoli species complex, including Rhizobium etli CFN42 and Rhizobium phaseoli VMW4, whereas the commercial strain HB429 clusters tightly with the Rhizobium etli strain HBR51.
Tag: crop yield
Upscaling of agar orchard to agroforestry systems for improving productivity and land use efficiency in the Brahmaputra floodplain of Bangladesh
The commercial plantation of agar trees has been increasing in the Brahmaputra floodplain under the greater Mymensingh region of Bangladesh. Agar plantation in the plainland allows enough space for cultivating different crops in between the two rows of agar trees. The present field study transformed a commercial agar (Aquilaria malaccensis Roxb.) plantation into agroforestry systems, where the performance of winter vegetables (radish, spinach, broccoli, and tomato) and the annual crop papaya were evaluated at different distances from the tree row. Afterward, it was compared with their respective non-agroforestry sole crops planted in open-field (control) conditions. The findings of the investigation revealed that the yield reduction for radish, spinach, broccoli, and tomato was 40%, 58%, 37%, and 40%, respectively, in agroforestry systems compared to the control. The yields of the seasonal crops were boosted with increasing planting distances from tree rows. These findings also indicated that the light intensity, which is indispensable for crop production, was highly interfered with in the agroforestry system by the straight canopy structure of agar trees. Though having some adverse impacts on yield performances of seasonal crops, the net return, benefit–cost ratio (BCR), and land equivalent ratio (LER) were greatly higher in agar-based agroforestry systems compared to non-agroforestry systems. Compared to non-agroforestry control plots, the total nitrogen, phosphorus, and potassium content in agroforestry systems was 41%, 27%, and 150% higher, respectively. Thus, it can be concluded that the Aquilaria plantation can be transformed into an agroforestry system to ensure higher income, optimum land use, and soil fertility status, and sustain food security.
Footprints of meteorology and air pollution on rice yield variation in the North Indian Plain; implications of future climate change scenarios
The global food system faces challenges from climate change and air pollution. Here, we examined their effects on rice yield in the North Indian plain (NIP), one of the principal rice-growing areas of the world. Combining satellite-based biophysical data products and spectral indices with soil moisture and fertilizer usage, we mapped high-resolution rice yield indiscriminately for both irrigated and rainfed systems in the NIP during the summer monsoon from 2004 to 2019. The footprints of meteorology and air pollution on the changing patterns of rice yield were isolated through multivariate linear models. The forced components of these models led to the estimation of relative yield change (RYC), the course of which was later simulated for the future climate change scenarios using CMIP6 data up to 2035. The largest effect on rice yield was estimated due to the variability of maximum temperature (−35 kg ha−1 to 212 kg ha−1) in the meteorological model, followed by aerosol loading (−80 kg ha−1 to 7 kg ha−1) in the air pollution model. The analysis of the RYC and its sensitivity using the CMIP6 climate change scenarios (SSP2 and SSP5) shows that among all agroclimatic regions, the Lower Gangetic Plain in the eastern NIP is resilient to the variability of meteorology and air pollution, while other agroclimatic regions – in the central and western NIP – show a remarkable reduction in their projected yields by 2035. The findings have serious implications for the supply chain and may increase pressure on the grain import due to climate change-driven future states of meteorology and air pollution.
Agricultural intensification in the Sahel: Suggestions for stakeholders
Key messages
- More trees and shrubs on farmland increase soil organic matter and crop production. However, crop yields can be further increased with small amounts of spot-applied mineral fertilizer (microdosing).
- Farmer managed natural regeneration provides a firm foundation for further intensification. It is clear from research that nutrient use efficiency and rainfall-use efficiency depend on adding organic matter to soils, and particularly to sandy soils. However, over most of the Sahel, it is challenging to produce enough manure and biomass – at least until the arrival of newly regenerating trees and shrubs.
- Projects z to improve soil fertility should do so in tandem with promoting farmer managed natural regeneration, or do it in existing agroforestry parklands.
- As fertilizer prices increase, African smallholders find greater value in nitrogen-fixing trees.
Agronomic levers to increase maize and soybean productivity across the Chinyanja Triangle, southern Africa
This study characterizes maize and soybean production systems in the Chinyanja Triangle, a major agricultural region spanning parts of Malawi, Zambia, and Mozambique, and evaluates opportunities to sustainably increase crop productivity. Maize is the principal staple crop in southern Africa, while soybean is rapidly expanding because of its economic and nutritional value. Using crop-cut measurements from 485 maize fields and 509 soybean fields, farmer surveys, climate and soil data, and simulations with the DSSAT crop model, the study assessed actual yields, yield gaps, and the main factors limiting production. Machine-learning approaches were applied to identify key drivers of yield variability and diagnose production constraints across locations. The study identifies practical agronomic interventions that can help reduce yield gaps and improve crop performance across diverse farming environments. These findings provide evidence to guide technology development, extension services, and agricultural investment strategies aimed at enhancing sustainable intensification, strengthening smallholder livelihoods, and improving regional food security in southern Africa.
The effect of short rotation Sesbania sesban planted fallows on maize yield.
Two provenances of Sesbania sesban var. nubica (Kakamega and Chipata) were planted in fallows for 1, 2 and 3 years at 0.5 m × 0.5 m, 0.7 m × 0.7 and 1.0 m × 1.0 m spacing. Maize crop (MM604) was grown after fallow period at 0, 37, 74 and 112 kg N ha1 to evaluate the effects of nitrogen (N) and fallow on grain yield. There were no significant differences between the two provenances of S. sesban. Wood biomass after 1, 2 and 3 years fallow at close spacing was 8.3, 17.6 and 21.4 t ha1 for the Kakamega provenance and 10.8, 14.5 and 21.2 t ha1 for the Chipata provenance. Litter fall in both provenances ranged from 0.6 t ha1 in June to 0.01 t ha1 in November. Stand mortality increased with plant density and fallow years: 27% in the first year and about 90% by the end of the third year. Weed biomass ranged from 6.8 t ha1 to 6.0 t ha1 at close and wide spacing respectively.Maize grain yield without N was 2.27, 5.59 and 6.02 t ha1 after 1, 2 and 3 years fallow respectively compared with the control plots with 1.6, 1.2. 1.8 t ha1 after 1, 2 and 3 years of continuous cropping. Even with addition of 112 kg N ha1, yield in the control plots declined from 6.09 to 4.88 and 4.28 t ha1 after 1, 2 and 3 years of continuous cropping. In the planted fallows at 112 kg N ha1, maize yield increased from 6.75 to 7.16 and 7.57 t ha1 following 1, 2 and 3 years fallow. It is concluded that short fallow rotations of 1–3 years using S. sesban have a potential in increasing maize yield even without fertilizers. Thus, increasing the fallow period decreases the effectiveness of inorganic fertilizers but increases grain yield for low fertilizer input.
Relating preseason soil nitrogen to maize yield in tree legume-maize rotations
Legumes can be an important source of N for cereals in tropical, subsistence farming systems that use little or no fertilizers. Our objective was to identify measures of soil N availability, following growth of diverse legumes, that correlated with yield of a subsequent unfertilized maize (Zea mays L.) crop. Unfertilized maize followed nine 3-yr-old systems (six monocultures of planted trees legumes, a groundnut [Arachis hypogea L.]-maize-soybean [Glycine max (L.) Merr.] rotation, an uncultivated fallow with natural regrowth of vegetation, and unfertilized maize monoculture) in two experiments on a Ustic Rhodustalf in eastern Zambia. Total soil C and N before maize planting were not related to grain yield of maize. Preseason soil inorganic N (NO3 + NH4), aerobic N mineralization, and light-fraction N (N in macroorganic matter, 150–2000 µm and <1.37 Mg m-3) at 0- to 15- cm depth correlated (P < 0.01) with maize grain yield. Preseason inorganic N combined with light-fraction N accounted for 59% of the variance in maize grain yield. The predictability of maize yield was slightly improved (64% of the variance) by including the population of the parasitic weed striga [Striga asiatica (L.) Kuntze] with preseason inorganic N and light-fraction N. The results suggest that yield of unfertilized, rain-fed maize following different rotational systems on a N-limiting soil in an area with monomodal rainfall was strongly related to the additive effects of preseason soil inorganic N and a soil N fraction related to N mineralization.
Effect of intercropping maize and closely spaced Leucaena hedgerows on soil conservation and maize yield on a steep slope at Ntcheu, Malawi
A six-year soil conservation trial was conducted on a steep slope, 44 percent, with a subhumid climate, based on very closely spaced (90 cm) hedgerows, using three intraspecific hybrids of Leucaena leucocephala. Soil loss averaged 2.0 t/ha per year on the Leucaena plots compared with an initial 80 t/ha per year on the unprotected control plot, falling to 27 t/ha per year after the top soil had been eroded. After 6 years, micro terraces of 35 cm high and 81 cm wide had developed on the intercropped plots, with substantially improved soil properties. Maize yield (unfertilized) were maintained at 1.5-2.0 t/ha on the protected plots, compared with a progressive fall from 0.8 to 0.5 t/ha on the sole maize control.
Intercropping with legumes in the Congo Basin increases maize yields but not greenhouse gas emissions
Agricultural intensification on existing arable lands has been proposed to reduce deforestation in the Congo Basin, although the effects of intensification on soil greenhouse gas (GHG) emissions have not yet been investigated. Here, we present the first field study to quantify the trade-offs between yield and GHG emissions across different intensification options in this region. We show that intercropping with nitrogen-fixing beans not only provided additional protein-rich food but also increased maize yields by 1.4-fold while leaving N2O emissions and the soil CH4 sink unchanged compared to unfertilized maize. In contrast, a moderate mineral fertilizer application of 66 kg N ha−1 yr−1 doubled yields, but reduced the soil CH4 sink strength, and increased N2O emissions fivefold to about 4 kg N2O-N ha−1 yr−1. These N2O emissions also exceeded those of natural forests by more than a factor of three, highlighting the GHG cost of mineral fertilizer use in addition to CO2 emissions from soil organic carbon loss following land conversion. In sum, intercropping with nitrogen-fixing beans had the lowest yield-scaled GHG emissions and can help to address protein malnutrition in regions with limited access to mineral fertilizers or particularly high N2O emissions.
Does Biochar Application Improve Paddy Productivity and Net Returns? An On-Farm Evidence and Farmers’ Perceptions in India
Transforming agricultural waste into biochar can potentially generate renewable energy, capture carbon, improve soil health, and mitigate climate change. However, its adoption is still minimal due to ambiguity in the realisation of associated benefits, as the evidence of its impact on crop yield based on on-farm data is very limited. In this study, we analysed a comprehensive dataset of 962 households across three states of India, viz. Madhya Pradesh, Maharashtra, and Odisha. Findings show that the application of biochar had a positive and significant effect on crop yield enhancement (4.34%) and net return (29.34%), and a reduction in cost of cultivation (1.52%). However, the effect size is much smaller than that reported in experimental studies conducted in controlled conditions. Farmers who are more experienced in farming, have irrigation facilities, and diversify crops and enterprises perceive benefits from biochar. Improvement in soil fertility is the primary benefit farmers perceive from biochar, whereas the limited availability of biochar and lack of incentives are the major constraints in adoption. The study suggests strategies and policies for outscaling and creating enabling environments for biochar production in Indian agriculture.