Marginal Soils Research Articles

Contribution to Improving the Chickpea (Cicer arietinum L.) Efficiency in Low-Phosphorus Farming Systems: Assessment of the Relationships between the P and N Nutrition, Nodulation Capacity and Productivity Performance in P-Deficient Field Conditions

Chickpea (Cicer arietinum L.), the third largest produced pulse worldwide, is primarily grown on marginal soils often characterized by a phosphorus (P)-deficiency that severely hampers yields. The objectives of the study are to investigate the relationships between the P-acquisition, P-use efficiency (PUE) and the agronomical performances towards the developing varieties tolerant to the P-deficiency. We evaluate the impact of the P-deficiency on the growth, yield, germination and nodulation performances of seven chickpea cultivars grown in fields with a low-P soil availability, during two seasons. The adaptive mechanisms to maintain the efficiency of the physiological processes, such as the nitrogen (N)-fixing nodule function, germinability, and possibly photosynthesis, are revealed. In contrast, the large genotypic variation in the yield components, in the P and N acquisition, and in the PUE is observed, supporting the role of the nodules in the P uptake in P-deficient soils. The P-acquisition and utilization efficiencies are genetically decoupled, suggesting designing distinct breeding strategies to promote one or both PUE components. As an outcome, we identify a set of chickpea cultivars adapted to a region with a soil P scarcity, that exhibit efficient N and P metabolism and a superior productivity. This germplasm can be used in breeding programs for low-P input efficient chickpeas. This contributes to the implementation of eco-friendly farming practices while making the most of marginal soils.

Effects of soil physics, chemistry, and microbiology on soil carbon sequestration in infertile red soils after long‐term cultivation of perennial grasses

AbstractDetermining the effect of perennial energy crop (PEC) cultivation on soil organic carbon (SOC) in marginal land soil is vital for carbon neutrality and bioeconomy development. However, a comprehensive and systematic evaluation of the response of SOC content to different PECs and its underlying drivers is still lacking. We used soil data collected from infertile red topsoil (0–20 cm) after 10 years of cultivation with Miscanthus (MS), Panicum virgatum (SG), and Saccharum arundinaceum (SA) to explore the changes in SOC stock induced by PEC. The roles of physical, chemical, and microbiological factors driving the increase in the SOC stock were investigated. Results revealed that SA and MS enhanced SOC stock by 87.97% and 27.52% relative to the uncultivated control. Conversely, PEC increased the percentage of soil mega‐aggregates, geometric mean diameters, soil chelate iron (Fe), and aluminum (Al) oxides, and reduced soil acidity for the infertile red soils. In addition, fungal richness and diversity for PEC soils were enhanced compared to the unplanted soil. It is possible that PEC cultivation reduced the relative abundance of copiotrophic fungi but increased the relative abundance of oligotrophic fungi. Furthermore, variance partitioning analysis revealed that chemical and microbiological factors accounted for 80.54% of the total variation for the SOC stock. The partial least squares path model showed that PEC cultivation enhanced soil carbon (C) stock via soil deacidification and increased soil bacterial function. In conclusion, this study confirms the SOC sequestration potential of PEC cultivation in marginal land and the underlying mechanism driving SOC stock. The main positive factors controlling soil C sequestration included “pH,” while the negative factors were “bacterial community,” “fungal community,” and “bacterial function.” Our research may help encourage and support decision‐makers of wasted marginal land conversion to PEC cultivation.

Grazing season length and stocking rate affect milk production and supplementary feed requirements of spring-calving dairy cows on marginal soils

The objective of this study was to investigate the effect of increasing stocking rate (SR) and extending grazing season (GS) length on pasture and animal productivity on a marginal, poorly draining soil type. The study was a multiyear (2017 to 2020, inclusive) whole farm systems evaluation with a 2 × 2 factorial experimental arrangement of treatments. The systems evaluated comprised 2 GS lengths, average (AGS; 205 d) and extended (EGS; 270 d), and the 2 whole farm stocking rates were medium (2.5 cows/ha) and high (2.9 cows/ha). We used this study design to create 4 grazing system intensities (500, 600, 700, and 800 cow grazing days per hectare per year). In 2017, cows were randomly allocated to 1 of the 4 whole farm systems precalving and remained on the same treatments for the duration of the study. We found no significant differences in total average annual pasture production [14,133 ± 538 kg of dry matter (DM) per hectare] or sward chemical composition between GS and SR treatments over the 4-yr period, with the exception of average crude protein content, which was lower for EGS (211 g/kg DM) compared with AGS (218 g/kg DM). Grazed pasture production was significantly increased in EGS treatments (+758 kg of DM/ha) compared with AGS (9,917 kg of DM/ha), whereas conserved silage DM production was greater for AGS (+716 kg of DM/ha) compared with EGS (3,583 kg of DM/ha). Neither GS nor SR had a significant effect on daily or cumulative lactation milk and fat plus protein production per cow (5,039 and ±440 kg, respectively). Increasing SR resulted in increased milk fat plus protein yield per hectare based on increased grazed pasture utilization. These results add further credence to the important additive contributions of both extended grazing and SR intensification to achieve high levels of grazed pasture utilization and milk production per hectare while reducing supplementary feed requirements within spring-calving grazing systems.

Multiple interval mapping of QTLs and epistasis for iron toxicity tolerance in segregating population of Indica rice

The global average temperature has increased by approximately 0.5 °C, over a last few decades and is projected to continue to increase. Environmental stress factors such as, elevated temperature, salinity, toxic elements (Fe, Al, Cd, Cr, Pb, Zn and As), drought and rising CO2 affect plant growth and make a growing threat to agriculture. Rice is a primary food crop in the world and the establishment of rice crop in acidic soil and in marginal soil is a major goal for the improvement of rice production to fulfill the food security. Among environmental stresses, Fe2+ toxicity is one of the main stresses in limiting the cereal crops production. Tolerant rice genotypes that can tolerate the high concentration of Fe2+ toxicity are the potential source genes for rice tolerance improvement in Fe2+ toxicity. In this research work, the genetic basis of seed germination traits and growth traits was investigated in rice using (multiple interval mapping) MIM. Many rice genotypes serve as source of tolerant against toxic metal ion like Fe2+, could be an important factor in controlling the sever effect of Fe2+ toxicity on germination and seedling growth traits. The F3 progenies of cross between Fe2+ toxicity tolerant cultivar ‘Pokkali’ and susceptible cultivar ‘Pak basmati’ were test against the optimized level of Fe2+ toxicity at germination, to determine the mode of inheritance to Fe2+ toxicity tolerance. Wide range of continues variation was found in F3 progenies. Among the 49 quantitative germination trait and 23 growth trait loci (QTLs) on chromosomes 1, 2, 4, 6, 8 and 9 linked with tolerance to Fe2+ toxicity was mapped. Additionally, 21 QTLs for germination traits and 9 QTLs for growth traits were classified as major QTLs using MIM. For germination and growth traits, notable epistasis between the chromosome 1, 2, 4, 6 and 11 was detected across germination and growth traits. Our results suggest that the tolerance mechanisms at germination and seedling phases could differ for Fe2+ toxicity. QTLs detected in this study for germination and seedling growth could be a source of new alleles for development of tolerance rice to Fe2+ toxicity varieties and transformation, gene cloning and gene editing in the future

Ligno-Cellulose Quality and Calorific Value ofElymus elongatusL. and the NovelSecale cereanumTested Under Central European Conditions

AbstractThe objective of the paper is to determine ligno-cellulose quality and calorific value of tall wheatgrass Szarvasi-1 and Alkar, as well as perennial rye Kriszta and Gergő cultivars, tested within a huge pilot field experiment. The experiment was established in the autumn of 2016 and was carried out until 2020, while four trial sites with marginal soil and three nutrition treatments (intensive, semi-intensive and untreated control) were included as well. The impact of the nutrition, years, sites, and cultivars on quality was statistically evaluated as the main effects, with two complete data set points of acid-detergent fibre (ADF), acid-detergent lignin (ADL), crude cellulose (CE), hemicellulose (HEM), neutral-detergent fibre (NDF) and high heating value (HHV), primarily in terms of quality content and a secondarily in terms of quality yield. In terms of quality content, the impact decreased in alternating order: of sites, years, and cultivars, each of them over the least important nutrition, while in terms of quality yield nutrition has been confirmed as the most important factor followed by sites, then by years, and finally by cultivars with the least impact. Average ADF content according to cultivars sequence Szarvasi-1 – Alkar – Kriszta – Gergő was 45.95 – 45.65 – 42.25 – 42.97%, ADL 8.67 – 8.24 – 8.51 – 8.37%, CE 37.27 – 37.41 – 33.74 – 34.60%, HEM 24.14 – 24.78 – 25.46 – 25.00%, NDF 70.03 – 70.43 – 67.71 – 67.71% and HHV 16.86 – 16.89 – 17.21 – 17.17 MJ/kg, respectively. The maximum yield values of ADF yield according to the order were 6.373 – 6.180 – 6.112 – 4.983 t/ha, ADL 1.340 – 1.374 – 1.261 – 1.027 t/ha, CE 5.253 – 5.111 – 4.851 – 3.997 t/ha, HEM 3.000 – 3.097 – 3.052 – 2.655 t/ha, NDF 9.285 – 9.133 – 9.164 – 7.626 t/ha and HHV 225.3 – 221.1 – 228.9 – 185.7 GJ/ha, respectively.

Genome-wide transcriptome analysis of the orphan crop tef (Eragrostis tef (Zucc.) Trotter) under long-term low calcium stress

Calcium (Ca2+) is one of the essential mineral nutrients for plant growth and development. However, the effects of long-term Ca2+ deficiency in orphan crops such as Tef [(Eragrostis tef) (Zucc.) Trotter], which accumulate high levels of Ca in the grains, remained unknown. Tef is a staple crop for nearly 70 million people in East Africa, particularly in Ethiopia and Eritrea. It is one of the most nutrient-dense grains, and is also more resistant to marginal soils and climatic conditions than main cereals like corn, wheat, and rice. In this study, tef plants were grown in a hydroponic solution containing optimum (1 mM) or low (0.01 mM) Ca2+, and plant growth parameters and whole-genome transcriptome were analyzed. Ca+2-deficient plants exhibited leaf necrosis, leaf curling, and growth stunting symptoms. Ca2+ deficiency significantly decreased root and shoot Ca, potassium (K), and copper content in both root and shoots. At the same time, it greatly increased root iron (Fe) content, suggesting the role of Ca2+ in the uptake and/or translocation of these minerals. Transcriptomic analysis using RNA-seq revealed that members of Ca2+ channels, including the cyclic nucleotide-gated channels and glutamate receptor-like channels, Ca2+-transporters, Ca2+-binding proteins and Ca2+-dependent protein kinases were differentially regulated by Ca+2 treatment. Moreover, several Fe/metal transporters, including members of vacuolar Fe transporters, yellow stripe-like, natural resistance-associated macrophage protein, and oligo-peptide transporters, were differentially regulated between shoot and root in response to Ca2+ treatment. Taken together, our findings suggest that Ca2+ deficiency affects plant growth and mineral accumulation by regulating the transcriptomes of several transporters and signaling genes.

Improving nitrogen retention of cattle slurry with oxidized biochar: An incubation study with three different soils.

The application of livestock slurry in soils can lead to nitrogen (N) losses through ammonia (NH3 ) emission or nitrate (NO3 - ) leaching. Oxidized biochar has great potential to mitigate N losses due to its strong adsorption capacity; however, the effects of oxidized biochar in different soils treated with slurry are currently unclear. Here, we investigated the effect of untreated and oxidized biochar (applied at a rate of 50kg C m-3 slurry) on reducing N losses in a laboratory experiment with three different soils (loamy sand, sandy loam, loam) amended with cattle slurry at an application rate of 73kg N ha-1 . Oxidized biochar reduced NH3 emissions by 64-75% in all soils, whereas untreated biochar reduced NH3 emissions by 61% only in the loamy sand. Oxidized biochar significantly reduced the NO3 - content in the soil solution of the loamy sand in the early phase of the incubation and led to a significantly higher NO3 - concentration in the same soil compared with the slurry-only treatment at the end of the experiment, indicating a significant increase in NO3 - retention in this organic C-poor soil. We conclude that oxidized biochar can reduce N losses, both in the form of NH3 emission and NO3 - leaching, from cattle slurry applied to soil, particularly in soil with soil organic carbon content<1% and pH<5 (i.e., oxidized biochar can serve as a means for improving the quality of marginal and acidic soils).

New Insights into the Phosphorus Acquisition Capacity of Chilean Lowland Quinoa Roots Grown under Low Phosphorus Availability.

Reducing phosphate fertilizer inputs while increasing food nutritional quality has been posited as a major challenge to decrease human undernourishment and ensure food security. In this context, quinoa has emerged as a promising crop due to its ability to tolerate different stress conditions and grow in marginal soils with low nutrient content, in addition to the exceptional nutritional quality of its grains. However, there is scarce information about the phosphorus acquisition capacity of quinoa roots. This work aimed to provide new insights into P acquisition and functional root traits, such as root biomass, rhizosphere pH, carboxylate exudation, and acid phosphatase activity of thirty quinoa genotypes grown under P limiting conditions (7 mg P kg-1). Significant genotypic variation was observed among genotypes, with average P accumulation ranging from 1.2 to 11.8 mg. The shoot biomass production varied more than 14 times among genotypes and was correlated with the P accumulation on shoots (r = 0.91). Despite showing high variability in root traits, only root biomass production highly correlated with P acquisition (r = 0.77), suggesting that root growth/morphology rather than the measured biochemical activity possesses a critical role in the P nutrition of quinoa.

Effects of different pioneer and exotic species on the changes of degraded soils

Soil degradation resulting from deforestation contributes to a dramatic decline in soil quality whose restoration must go through reforestation with pioneer species. We investigated the effects of cypress and black locust, pioneer but exotic species, on soil chemical properties and microbial and enzymatic activities of two marginal soils. The sampling sites were Lama Giulia and Locone lake in the Murge plateau of the Apulia Region, Italy. The soils at Lama Giulia presented a silty loam texture, while at Locone Lake site were sandy, and most likely due to the different texture, the former exhibited higher organic C, N, P and micronutrients contents than Locone Lake under black locust reforestation, despite the latter was reforested earlier. In addition, the higher microbial entropy and turnover of Locone Lake’s soils suggested a less conservative soil state than Lama Giulia’s soils. The effects of black locust reforestation at Lama Giulia on almost all soil parameters considered did not differ from those of the corresponding pasture, confirming the more conservative soil state in that site and suggesting that the time of reforestation was not enough to get differences between the reforested and not reforested soil. The soils reforested with cypress showed the significantly highest SOC, N, dissolved organic C and microbial biomass C content. In addition, it presented also the numerically largest dehydrogenase, phosphatase and β-glucosidase activities, soluble carbohydrates, and phenolic compounds content. These results may be ascribed to the longer litter deposition occurred in cypress soils.

A review of the adaptive capacity of sweet sorghum to improve food security and poverty alleviation in sub-Saharan Africa

• Sweet sorghum can address socioeconomic challenges for African smallholder farmers. • A neglected multiuse crop, it is utilised for food, fuel, fibre, and fodder. • This grain crop can grow under water limited- and low nutrient input conditions. • Adoption of sweet sorghum in smallholder farming requires investment in research. Current challenges facing smallholder farmers in sub-Saharan Africa (SSA) require holistic adoption of crops that have diverse socioeconomic and agronomic significance. Sweet sorghum, an underutilised grain crop, has such potential, especially for bioethanol production, due to its adaptation to harsh conditions. Despite being native to SSA, its neglect and underuse is a concern given its wide potential to improve socioeconomic conditions of farmers in this region. This review highlights sweet sorghum's potential by discussing its adaptive capability against major production constraints such as water availability, soil nutrition, plant population, planting date, and harvest time. The review highlights sweet sorghum as a crop that maximises its growth and development under water stress conditions due to its high-water use efficiency. Furthermore, sweet sorghum can be cultivated under marginal soils compared to its biofuel counterparts (e.g., maize, sugarcane, and sugar beet) and can still be high yielding (grain) at high plant densities, with early planting dates also resulting in high yields. These attributes are significant in smallholder farming systems due to their susceptibility to socioeconomical and agronomic challenges. In addition, it was identified that there is lack of research relating to pests and diseases that plague sweet sorghum, with some measures and recommendations being based on grain sorghum. Therefore, the need for research and development on sweet sorghum in SSA may not only intensify its benefits to farmers but can also improve efficient cultivation under local environmental conditions.

Plant Growth-Promoting Bacteria (PGPB) integrated phytotechnology: A sustainable approach for remediation of marginal lands.

Land that has little to no utility for agriculture or industry is considered marginal land. This kind of terrain is frequently found on the edge of deserts or other arid regions. The amount of land that can be used for agriculture continues to be constrained by increasing desertification, which is being caused by climate change and the deterioration of agriculturally marginal areas. Plants and associated microorganisms are used to remediate and enhance the soil quality of marginal land. They represent a low-cost and usually long-term solution for restoring soil fertility. Among various phytoremediation processes (viz., phytodegradation, phytoextraction, phytostabilization, phytovolatilization, phytofiltration, phytostimulation, and phytodesalination), the employment of a specific mechanism is determined by the state of the soil, the presence and concentration of contaminants, and the plant species involved. This review focuses on the key economically important plants used for phytoremediation, as well as the challenges to plant growth and phytoremediation capability with emphasis on the advantages and limits of plant growth in marginal land soil. Plant growth-promoting bacteria (PGPB) boost plant development and promote soil bioremediation by secreting a variety of metabolites and hormones, through nitrogen fixation, and by increasing other nutrients' bioavailability through mineral solubilization. This review also emphasizes the role of PGPB under different abiotic stresses, including heavy-metal-contaminated land, high salinity environments, and organic contaminants. In our opinion, the improved soil fertility of marginal lands using PGPB with economically significant plants (e.g., Miscanthus) in dual precession technology will result in the reclamation of general agriculture as well as the restoration of native vegetation.

Di-ammonium phosphate (DAP) and plant density improve grain yield, nodulation capacity, and profitability of peas (Pisum sativum L.) on ferralsols in eastern D.R. Congo

Sustaining high crop yield and profitability on marginal soils, such as degraded ferralsols, calls for the use of adequate farming practices. In this study, we assessed for four cropping seasons the effect of di-ammonium phosphate (DAP) fertilizer application doses (100, 150, and 200 kg ha−1) and plant densities (100,000, 166,666, and 250,000 plants ha−1) on growth, yield, nodulation capacity, and profitability of two pea varieties (Adei and Rwanda) under degraded ferralsols in eastern Democratic Republic of Congo (DRC). Results showed that pea growth, yield, nodulation, and profitability were significantly affected by the DAP dose and the plant density. Application of 150 kg ha−1 of DAP improved pea yields from 730 to 1720 kg ha−1 and nodulation from 17 to 22 nodules per plant. The number of active nodules was positively correlated with total number of nodules, DAP doses, yield parameters, and plant height. High grain yield was recorded during the long rainy season (1400 kg ha−1) compared to the short one (930 kg ha−1). All DAP doses were profitable according to the agronomic efficiency (AE) and value–cost ratio (VCR) analyses. For improved and profitable pea production on degraded South-Kivu ferralsols, applying 150 kg ha−1 of DAP combined with low plant density are to be recommended and preferably in the long rainy season.

Combined Application of Inorganic and Organic Phosphorous with Inoculation of Phosphorus Solubilizing Bacteria Improved Productivity, Grain Quality and Net Economic Returns of Pearl Millet (Pennisetum glaucum [L.] R. Br.)

Pearl millet (Pennisetum glaucum [L.] R. Br.) is a climate-smart cereal crop for environments prone to drought and heat stresses. Pearl millet is cultivated in Pakistan on marginal soils with phosphorus (P) deficiency, which significantly decreases its productivity. Moreover, P fixation in the country’s calcareous soils is another major constraint which requires attention. P solubilizing bacteria (PSB) have the potential to improve P availability in the soil. However, the potential of PSB in improving P availability in soil and pearl millet yield has been rarely tested in Pakistan. Therefore, this 2-year field study explored the role of combined application of organic and inorganic P sources along with PSB (i.e., Bacillus sp. MN54) inoculation to improve yield-related traits, P use efficiency (PUE), net economic returns and grain quality of pearl millet grown under semi-arid climatic conditions. Phosphorus was applied through inorganic sources, organic sources (farmyard manure) and 50% inorganic sources + 50% organic sources with or without PSB inoculation. In control treatment, pearl millet was grown without P application. The individual and combined application of P from different sources and PSB inoculation significantly improved yield-related traits and PUE of pearl millet. The highest grain yield was observed with combined (50% inorganic + 50% organic) application of P with PSB inoculation. The same treatments resulted in higher iron, zinc, protein and P contents in the grains during both years. Likewise, P application through organic and inorganic sources combined with PSB inoculation improved soil bulk density, fertility and microbial population during both years. The highest economic returns and benefit–cost ratio was recorded for combined P application (50% inorganic + 50% organic) and PSB inoculation. In crux, the combined application of organic and inorganic P fertilizers along with PSB (Bacillus sp. MN54) inoculation seemed a feasible approach to enhance productivity, grain quality and net economic returns of pearl millet. Therefore, it is recommended that P should be applied through both organic and inorganic sources combined with PSB inoculation to improve P availability and productivity of pearl millet in Pakistan. The current study has explored the potential of combined P application through organic and inorganic sources along with PSB inoculation. Future studies should focus on the determination of mobilized P with the application of PSB.

A hyperbolic model for mechanical behaviour of marginal soil-geosynthetic interface

Locally available marginal soils are of great interest to use as backfill material in geosynthetic reinforced soil structures due to their cost-effectiveness. The advanced stress–strain analysis of these structures necessitates the correct evaluation and the accurate description of marginal soil-geosynthetic interface behaviour. Therefore, the primary objectives of this study are numerical and analytical analysis of the soil-geosynthetic interface behaviour with application of a hyperbolic nonlinear elastic perfectly plastic constitutive model. In this investigation a series of large-scale direct shear tests was performed to evaluate the shear stress-displacement interface behaviour considering two types of marginal soils in contact with five types of geosynthetic materials in different soil moisture conditions. Accordingly, the hyperbolic model was used to simulate the soil-geosynthetic interface behaviour. Moreover, a three-dimensional finite element model of the direct shear test was developed using ABAQUS software and a user-defined subroutine was implemented to consider the hyperbolic interface model. The results indicated a very good agreement between the experimental data and the predicted finite element simulations of the direct shear tests and analytical solutions. Finally, a numerical simulation of a pullout test is presented in this paper with application of the hyperbolic interface model.

Influence of Poultry Manure Application Rates on Red and Yellow Varieties of Watermelon (Citrullus lanatus) in the Marginal Mineral Soil of Bukit Kor (Marang)

Increased crop yields and higher soil quality can be achieved by using the appropriate amount of fertiliser at the right time. A study on optimal poultry fertiliser rates for watermelon development on nutrient deficient soil, contributes to the current knowledge base. Thus, this paper intends to ascertain the effect of different application rates of poultry fertilizer on growth and yield properties of two cultivars of watermelon (Citrullus lanatus) on soil with marginal nutrients. Accordingly, an experiment was conducted at Universiti Malaysia Terengganu's research farm at Bukit Kor (Marang) to compare the effects of various application rates (T1: 0T/Ha, T2: 10T/Ha, T3: 20T/Ha, T4: 30T/Ha) of poultry manure on the performance of two watermelon varieties (V1:yellow variety (golden delight) and V2:red variety (new dragon)). Several growth and yield parameters were determined, of which the treatments on the red variety at 20THa^-1 and 30THa^-1 produced the significant higher results for vine length (189.38 & 189.43cm), number of leaves (61 & 63), number of lateral branches (2.5 & 2.33), leaf area index (0.12 & 0.13), chlorophyll content SPAD (36.32 & 37.03), fruit weight (10.23 & 9.84THa^-1) and number of flowers (8.33 & 11.7). The present research, therefore, contributes to a growing body of evidence suggesting that the red variety of watermelon treated with 20THa^-1 or 30THa^-1 presented the best results.

Growth and yield of several Gogo rice varieties (Oryza Sativa L.) applicated by various P sources in Ultisol Planting Media

Gogo rice productivity is still low because farmers still use local varieties of Gogo rice and most of it is cultivated on marginal soils such as Ultisol. Ultisol soils contain low available P due to P fixation by Al and Fe. The existence of Gogo rice varieties that can compensate for the high Al content in Ultisol soil and can neutralize Al in plants is one of the right solutions in overcoming the problem of Al poisoning. While the constraint of the lack of availability of P nutrients in Ultisol requires the application of P fertilizer. This study aims to determine the growth and yield of several Gogo rice varieties given various P sources and to determine the best Gogo rice varieties and the best P sources in Ultisol. The research method used a Split Plot Design. The main plot is Gogo rice varieties consisting of three levels, namely; Kuku Balam, Dogor, and Inpago 10, as well as subplots are various sources of P consisting of four levels, namely; No P, 0.4 g TSP, 0.7 g rock phosphate, and 1.8 g guano. The results showed that administration of 0.4 g TSP was the best source of P in Gogo rice than without P, ​​administration of RP, and guano on the value of P nutrient uptake, maximum tillers, productive tillers, flowering age, harvest age, number of grains per panicle, percentage pithy grain, the weight of dry milled grain per clump and the ratio of grain and straw. The Kuku Balam variety had a nutrient uptake value of P (130.91 mg/clump), the number of grains per panicle (210.63 grains) and the weight of milled dry grain per clump (42.11 g) which were the best yields compared to the Dogor and Inpago 10.

Achieving the dual goals of biomass production and soil rehabilitation with sown pasture on marginal cropland: Evidence from a multi-year field experiment in Northeast Inner Mongolia.

Grassland is the primary land use in China but has experienced severe degradation in recent decades due to overgrazing and conversion to agricultural production. Here, we conducted a field experiment in northeastern Inner Mongolia to test the effectiveness of sown pastures in lowering the grazing pressure on grasslands and raising the quality of marginal soils. Alfalfa and smooth bromegrass monocultures and mixture were sown in a marginal cropland field in Hulunber in June 2016. Biomass productivity, soil physicochemical, and biological properties were monitored annually from 2016 to 2020. The results showed that the marginal cropland soil responded consistently positively to sown pastures for major soil properties. Soil organic carbon (SOC) and total nitrogen (TN) increased by 48 and 21%, respectively, from 2016 to 2020 over the 0-60 cm soil depth range. Soil microbes responded proactively too. The soil microbial biomass C (SMBC) and N (SMBN) increased by 117 and 39%, respectively, during the period of 2016-2020. However, by the end of the experiment, the soil of a natural grassland field, which was included in the experiment as a control, led the sown pasture soil by 28% for SOC, 35% for TN, 66% for SMBC, and 96% for SMBN. Nevertheless, the natural grassland soil’s productive capacity was inferior to that of the sown pasture soil. The average aboveground biomass productivity of sown pastures was measured at 8.4 Mg ha-1 in 2020, compared to 5.0 Mg ha-1 for natural grassland, while the root biomass of sown pastures was averaged at 7.5 Mg ha-1, leading the natural grassland by 15%. Our analyses also showed that the sown pastures’ biomass productivity advantage had a much-neglected potential in natural grassland protection. If 50% of the available marginal cropland resources in Hulunber under the current environmental protection law were used for sown pastures, the livestock grazing pressure on the natural grasslands would decrease by a big margin of 38%. Overall, these results represent systematic empirical and analytical evidence of marginal cropland soil’s positive responses to sown pastures, which shows clearly that sown pasture is a valid measure both for soil rehabilitation and biomass production.

Prospects of rhizobial inoculant technology on Bambara groundnut crop production and growth

After peanuts and cowpeas (Vigna unguiculata), the Bambara groundnut (Vigna subterranea (L.) Verdc) is the third most significant food legume in Africa. It is characteristically grown in marginal soils, is drought tolerant, and also has the potential for nitrogen fixation. Despite that, year-on-year Bambara groundnut yields are on a gradual decline due to a combination of abiotic and biotic stresses such as uneven annual rainfall and climate-induced changes in soil microbial community compositions, negatively impacting food security. Thus, the application of rhizobial inoculants at planting significantly improves yields in many leguminous crops. Moreover, symbiotic inoculants are well established in developed countries for improving nitrogen fixation and productivity in grain legumes. Sub-Saharan African countries, however, still under-utilise the above practice. In crop production, nitrogen (N) is the most frequently deficient nutrient since it stimulates root and shoots growth. Whereas nitrogen fertilisers can be used to supplement soil N levels, they are, however, also costly, at times inadequate, may not be timely in supply and may have deleterious environmental consequences. Hence, rhizobial inoculants are seen as a cheaper, easier, and safer method for improving N-fixation and crop productivity in grain legumes, as a result, smallholder farming systems are food secure. Thus, identifying the most efficient rhizobial strains for biofertiliser production for Bambara groundnut is of utmost importance to the farming communities.

Nutrient management and bioaugmentation interactively shape plant–microbe interactions inMiscanthus × giganteus

AbstractMarginal lands are an untapped source of agricultural potential, particularly regarding high‐yielding, low‐input bioenergy crops likeMiscanthus × giganteus(Miscanthus).Miscanthusis of specific interest because it can be productive and sequester carbon in soil even under the stressful conditions present on some degraded lands. A key component of these abilities is the interaction ofMiscanthuswith its soil and root microbiome. Microbial functions depend on the nutrient status of soil, and hence are sensitive to fertilization regimes. Nevertheless, little is known about how fertilization strategies affect the partnership ofMiscanthuswith its microbial associates. Here, we tested the individual and interactive effects of nutrient addition and bioaugmentation (i.e., the addition of microbial communities) onMiscanthusperformance and microbiome function in marginal soil. We found that the effect of nutrient addition onMiscanthusbiomass yield depended on nutrient addition type (i.e., organic or inorganic nutrients) and whether bioaugmentation was also applied. Some microbial functions, like free‐living nitrogen fixation and carbon use efficiency, were sensitive to nutrient addition depending on whether bioaugmentation was also applied. On the other hand, arbuscular mycorrhizal fungus colonization of roots decreased with fertilization regardless of bioaugmentation. These results imply that managing microbial communities may regulate the effect of nutrient addition on plant–microbe interactions that in part determine system productivity and environmental impact.

Diverged subpopulations in tropical Urochloa (Brachiaria) forage species indicate a role for facultative apomixis and varying ploidy in their population structure and evolution.

Urochloa (syn. Brachiaria) is a genus of tropical grasses sown as forage feedstock, particularly in marginal soils. Here we aimed to clarify the genetic diversity and population structure in Urochloa species to understand better how population evolution relates to ploidy level and occurrence of apomictic reproduction. We explored the genetic diversity of 111 accessions from the five Urochloa species used to develop commercial cultivars. These accessions were conserved from wild materials collected at their centre of origin in Africa, and they tentatively represent the complete Urochloa gene pool used in breeding programmes. We used RNA-sequencing to generate 1.1 million single nucleotide polymorphism loci. We employed genetic admixture, principal component and phylogenetic analyses to define subpopulations. We observed three highly differentiated subpopulations in U. brizantha, which were unrelated to ploidy: one intermixed with U. decumbens, and two diverged from the former and the other species in the complex. We also observed two subpopulations in U. humidicola, unrelated to ploidy; one subpopulation had fewer accessions but included the only characterized sexual accession in the species. Our results also supported a division of U. decumbens between diploids and polyploids, and no subpopulations within U. ruziziensis and U. maxima. Polyploid U. decumbens are more closely related to polyploid U. brizantha than to diploid U. decumbens, which supports the divergence of both polyploid groups from a common tetraploid ancestor and provides evidence for the hybridization barrier of ploidy. The three differentiated subpopulations of apomictic polyploid U. brizantha accessions constitute diverged ecotypes, which can probably be utilized in hybrid breeding. Subpopulations were not observed in non-apomictic U. ruziziensis. Sexual Urochloa polyploids were not found (U. brizantha, U. decumbens) or were limited to small subpopulations (U. humidicola). The subpopulation structure observed in the Urochloa sexual-apomictic multiploidy complexes supports geographical parthenogenesis, where the polyploid genotypes exploit the evolutionary advantage of apomixis, i.e. uniparental reproduction and clonality, to occupy extensive geographical areas.