Maize Shoot Biomass Research Articles

Azospirilla and Nitrogen Fertilization to Promote Maize Seed Development and Yield

Aims: This study evaluated the interaction of Azospirillum brasilense (Ab) strains and nitrogen fertilizer doses on maize.
 Study Design: Laboratory experiment evaluated Ab strains (PCR and PTF) on maize seed germination and vigor (completely randomized design). Field experiment evaluated Ab strains and nitrogen fertilization on maize yield parameters (randomized block design).
 Place and Duration of Study: The germination and vigor experiment (10 days in April 2019) was implemented in a controlled environment at the Seed Analysis Laboratory of the Universidade Federal de Uberlândia, Brazil. The field experiment (137 days in winter 2019) was implemented at the Fisioplant Research Station (Uberlândia, Brazil) under commercial maize crop management.
 Methodology: In controlled conditions (laboratory), 200 seeds of maize (K9105VIP3, Riber KWS Seeds) were incubated (25 °C) with the Ab strain solutions for germination and vigor evaluations. In the field, 60,000 plants ha-1 (0.5 m space between sowing lines) of maize were cropped under combinations of nitrogen fertilizer and volumes of Ab strains (treatments) for leaf nitrogen, SPAD index, leaf count, fresh and dry maize shoot biomass, one-thousand grains weight, grain rows per maize ear, productivity (kg ha-1).
 Results: Treatment with 100 mL ha-1 of Ab PFT strain increased maize seed germination and vigor more than Ab PCR strain and control (no-inoculation or fertilizer). The number of grain rows of the 100% N + 150 mL ha-1 of Ab PFT strain and the maize shoot dry mass of the 100% N (no-inoculation) were higher than the control. The treatments did not affect the SPAD index, weight of one thousand grains, fresh maize shoot biomass, or productivity.
 Conclusion: Using Ab with nitrogen fertilizer is a promising strategy to improve maize crop responses; however, more studies are needed to detail the ideal management of Ab strains for maize crops and yield construction.

Pb-resistant Pantoea rwandensis promotes maize's growth by altering Pb accumulation in biomass and soil Pb immobilization.

In lead (Pb)-contaminated soil, inoculating phosphate-solubilizing bacteria (PSB) to reduce the phytoavailability of Pb and to change the soil nutrients is an important way to inhibit the Pb uptake by plants. In this study, we isolated the native Pb-resistant Pantoea rwandensis from a tailings site. We employed broth culture and pot experiments to investigate the effect of the inoculation of P. rwandensis on Pb immobilization in the soil, the soil nutrients, the microbial community, and Pb accumulation in the biomass of maize (Zea mays L.). The results showed that P. rwandensis not only tolerated Pb2+ but also dissolved Ca3(PO4)2 by secreting oxalic acid, tartaric acid, lactic acid, and acetic acid, which significantly increased the amount of dissolved P, up to 567.50 mg.L-1. In the pot experiment, the application of culture filtrate, an inoculation with P. rwandensis, or a mixture of culture filtrate and P. rwandensis increased the soil residual Pb by 49.57%, 89.81%, and 41.69%, respectively, compared to the control. Consequently, the increase in the residual Pb in the soil inhibited its uptake by maize, and an inoculation of P. rwandensis or a mixture of culture filtrate and P. rwandensis decreased the accumulation of Pb in the shoot biomass of maize by 61.65% and 72.48% and in the roots of maize by 26.00% and 39.59%, respectively. Meanwhile, P. rwandensis and the mixture of culture filtrate and P. rwandensis increased the shoot biomass of maize by 54.39% and 17.86% and the root biomass of maize by 108.77% and 17.86%, respectively. A P. rwandensis inoculation increased the biodiversity of the fungal community and the abundance of Proteobacteria, Mortierella, and Sphingomonas. Our results demonstrate that an inoculation with P. rwandensis could promote the transformation of Pb fractions and a functional change in the soil bacterial community, ultimately decreasing Pb accumulation in the biomass and promoting the development of maize.

Contrasting effects of organic materials versus their derived biochars on maize growth, soil properties and bacterial community in two type soils.

The objective of this study was to assess the benefit of applying biochar instead of its feedstock in enhancing soil quality. To accomplish this, we investigated the short-term effects of two organic materials and their derived biochars on maize growth, soil properties, and microbial community in fluvo-aquic and red soil with a pot experiment. Five treatments were applied to each soil, namely, the addition of straw, manure, straw-derived biochar, manure-derived biochar, and the control with no addition of any organic materials and biochar. Our results revealed that straw decreased the shoot biomass of maize in both soils, while straw-derived biochar, manure and manure-derived biochar increased it by 51.50, 35.47 and 74.95% in fluvo-aquic soil and by 36.38, 117.57 and 67.05% in red soil compared with the control, respectively. Regarding soil properties, although all treatments increased soil total organic carbon, straw and manure exhibited more pronounced effects on improving permanganate-oxidizable carbon, basal respiration, and enzyme activity compared with their derived biochars. Manure and its biochar had more significant effects on improving soil available phosphorus, whereas straw and its biochar exhibited more ameliorating effects on available potassium. Straw and manure consistently decreased bacterial alpha diversity (Chao1 and Shannon index) and altered bacterial community composition in the two soils by increasing the relative abundances of Proteobacteria, Firmicutes, and Bacteroidota and decreasing those of Actinobacteriota, Chloroflexi, and Acidobacteriota. More specifically, straw had a greater effect on Proteobacteria, whereas manure affected Firmicutes more. While straw-derived biochar had no effect on bacterial diversity and bacterial community composition in both soils, manure-derived biochar increased bacterial diversity in the fluvo-aquic soil and altered bacterial community composition in the red soil by increasing the relative abundances of Proteobacteria and Bacteroidota and decreasing that of Firmicutes. In summary, owing to the input of active organic carbon, straw and manure exhibited more pronounced short-term effects on soil enzyme activity and bacterial community compared with their derived biochar. Furthermore, straw-derived biochar was found to be a better option than straw in promoting maize growth and nutrient resorption, while the choice of manure and its biochar should be determined by the soil type.

Rapeseed-maize double-cropping with high biomass and high economic benefits is a soil environment-friendly forage production mode in the Yangtze River Basin

The problem of the large area of winter abandoned fields in the Yangtze River Basin (YRB) has gotten worse. Moreover, there was no suitable annual forage crop planting pattern to fulfilling the annual forage needs of livestock and poultry production in the YRB region. Utilizing the abandoned field to develop high-quality and efficient forage crop planting patterns is significant. Herein as a first-time study, two growing seasons of five different double-cropping modes field experiments were performed with ryegrass-maize (RM), hairy vetch-maize (HM), rapeseed-maize (BM), milk vetch-maize (MM), and abandoned-maize (AM) to study their effects on forage production, soil properties, latter maize performance, and economic benefits. Rapeseed-maize double-cropping mode achieved the maximum annual biomass yield (37.0 Mg ha−1) and net profit value (33563 CNY ha−1), which is the most productive among the five double-cropping modes. The soil available phosphorus content after planting rapeseed was significantly higher than other modes, which was 65.6%, 37.0%, 1.5%, and 12.2% higher than abandoned field, ryegrass, hairy vetch, and milk vetch, respectively. There was a non-significant difference in soil penetration resistance (PR) between after planting rapeseed, hairy vetch, and milk vetch at the soil depth of 5–27.5 cm; whereas, the PR was reduced by 24.7% and 34.8% after planting rapeseed compared to abandoned field and planting ryegrass, respectively. Compared to the abandoned field, planting hairy vetch and milk vetch showed highly significant effects on suppression of weeds biomass and density in maize field followed by rapeseed, while planting ryegrass significantly increased the weeds biomass and density by 61.6% and 62.3%, respectively. The principal component analysis results indicated that the PR was negatively correlated to the soil fertility and maize growth traits, while positively correlated with weeds occurrence. Besides, the root activity, and root, shoot biomass of maize were significantly positively correlated with the soil fertility after harvesting winter crops. Therefore, rapeseed-maize double-cropping may be a productive pattern to promote annual forage production and enhance the agricultural economy in the Yangtze River Basin region.

Co‐amelioration of red soil acidity and fertility with pig manure rather than liming

AbstractLime (calcium oxide), animal manure and crop straw soil treatments have been shown to ameliorate soil acidity, yet their effectiveness at concurrently enhancing soil fertility status and improving crop yields is less well understood. In this study, an acidic nutrient deficient red soil (Ferralic Cambisol) received these treatments at various dosage rates (% of DW soil) in pot experiments with maize plants. Lime was applied at four dosage rates (0.05%, 0.10%, 0.15% and 0.20%), pig manure at three rates (0.50%, 1.00% and 1.50%), maize straw or milk vetch at two rates (0.50% and 1.00%) and combinations of lime (0.10% or 0.15%) with maize straw (0.50%) and/or pig manure (0.50%). Soils treated with and without chemical fertilizers were also included as controls. Measurements of soil pH, exchangeable acidity, plant available nutrients and maize shoot biomass were recorded. Maize shoot biomass increased by 4.7–7.6 times under pig manure treatments, 1.1–1.6 times under milk vetch, 0.4–1.5 times under lime and 1.1–6.2 times under combination treatments, compared with the control. Soil pH increased by 0.5–0.9 units under lime, by 0.2–0.4 units under pig manure and by 0.7 pH units under the combination treatment relative to the control. Variance partitioning analysis showed that on an individual basis, soil acidity amelioration (pH, exchangeable H+ and Al3+) or nutrient input (C, N, P, K, Ca, Mg, Zn) explained only 4.3% and 5.6% of improved maize growth, respectively. Whereas, their interaction explained 85.9% of the variation. We also report that the over‐application of pig manure could lead to P saturation and negative impacts on aquatic systems in the wider environment. Therefore, we recommend a combination of lime, pig manure and straw provides an optimal solution for addressing soil acidity and limiting P saturation in acid soils.

Combinational Variation Temperature and Soil Water Response of Stomata and Biomass Production in Maize, Millet, Sorghum and Rice

Environmental responses of stomatal conductance (gs) as basic information for a photosynthesis-transpiration-coupled model have been increasing under global warming. This study identified the impact of gs behavior under different soil water statuses and temperatures in rice, maize, millet, and sorghum. The experiments consisted of various soil moisture statuses from flooding to drying and combination of soil moisture status and temperature. There was a reduction in shoot biomass of maize and sorghum caused by decreasing of gs, photosynthesis (A), and transpiration (E) in early imposed waterlogging without dependent temperature, whereas millet and rice were dependent on temperature variation. The effect of gradual soil drying, gs, A, and E of maize, millet, and sorghum were caused by low temperature, except rice. The impact of the combination of various soil water statuses and temperatures on gs is important for the trade-off between A and E, and consequently shoot biomass. However, we discovered that an ability to sustain gs is essential for photo assimilation and maintaining leaf temperature through evapotranspiration for biomass production, a mechanism of crop avoidance in variable soil water status and temperature.

Waste to resource: use of water treatment residual for increased maize productivity and micronutrient content

Soil degradation, which is linked to poor nutrient management, remains a major constraint to sustained crop production in smallholder urban agriculture (UA) in sub-Saharan Africa (SSA). While organic nutrient resources are often used in UA to complement mineral fertilizers in soil fertility management, they are usually scarce and of poor quality to provide optimum nutrients for crop uptake. Alternative soil nutrient management options are required. This study, therefore, evaluates the short-term benefits of applying an aluminium-based water treatment residual (Al-WTR), in combination with compost and inorganic P fertilizer, on soil chemical properties, and maize (Zea mays L.) productivity and nutrient uptake. An eight-week greenhouse experiment was established with 12 treatments consisting of soil, Al-WTR and compost (with or without P fertilizer). The co-amendment (10% Al-WTR + 10% compost) produced maize shoot biomass of 3.92 ± 0.16 g at 5 weeks after emergence, significantly (p < 0.05) out-yielding the unamended control which yielded 1.33 ± 0.17 g. The addition of P fertilizer to the co-amendment further increased maize shoot yield by about twofold (7.23 ± 0.07 g). The co-amendment (10% Al-WTR + 10% C) with P increased maize uptake of zinc (Zn), copper (Cu) and manganese (Mn), compared with 10% C + P. Overall, the results demonstrate that combining Al-WTR, compost and P fertilizer increases maize productivity and micronutrient uptake in comparison with single amendments of compost and fertilizer. The enhanced micronutrient uptake can potentially improve maize grain quality, and subsequently human nutrition for the urban population of SSA, partly addressing the UN’s Sustainable Development Goal number 3 of improving diets.

Effect of sowing proportion on above- and below-ground competition in maize\u2013soybean intercrops

The relative contribution of above- and below-ground competition to crop yield under intercropping systems is critical to understanding the mechanisms of improved yield. Changes in the content of above- and below-ground biomass, leaf photosynthetic rate (Pn), leaf area index (LAI), chlorophyll meter reading (SPAD), diffuse non interceptance (DIFN), soil water storage (SWS), crop nitrogen (N), and phosphorus (P) uptake were examined in a 2-year trial of different maize–soybean intercropping systems on the Loess Plateau, China. Compared with the sole cropping system, shoot biomass of maize was increased by 54% in M2S2 and 62% in M2S4 strip intercropping treatment. The crop N and P uptake of maize increased significantly, by 54% and 50% in M2S2 and by 63% and 52% in M2S4 compared with their respective sole crop. LAI values of maize in intercropping systems were 14% and 15% for M2S2 and M2S4 less than that in the sole crop. The DIFN of intercropped maize was increased by 41% and 48% for M2S2 and M2S4 compared to monocrop. There were no significant differences in Pn and SWS in both crops between the two cropping systems. The contribution rate of DIFN in M2S2 and crop P uptake in M2S4 on the biological yield in intercropping system was the highest among all factors. We conclude that the sowing proportion affects above- and below-ground competition in maize–soybean intercropping systems.

Crop sulfur status in relation to soil sulfur determined using anion exchange membranes and Mehlich 3

The aim of this study was to find an indicator of plant sulfur status correlating most significantly with bioavailable sulfur in soil. The indicators of plant sulfur status in shoot biomass were: sulfur concentration, mass nitrogen to sulfur (N/S) ratio, mass phosphorus to sulfur ratio and sulfur nutrition index (SNI). The bioavailable soil sulfur was determined using water extraction (S-water), Mehlich 3 extractant (S-M3) and anion exchange membranes (S-AEMs). Results cover four years (2015–2018) of on-farm trials in the Czech Republic with winter wheat, winter oilseed rape and maize, and pot experiments including spring wheat and maize. Shoot biomass of plants was sampled at the beginning of stem elongation (winter wheat, winter rape and maize in on-farm trials), during rapid growth (maize in pot experiment) and during flowering (wheat plants, winter rape). Only soils containing 0.5%–1.7% of organic carbon were studied (median 1.31%). Compared to shoot N/S ratio, sulfur concentration in shoot biomass of maize correlated stronger with bioavailable soil sulfur. However, bioavailable sulfur in soil correlated strongest and most significantly with shoot N/S ratio of winter wheat and winter rape grown in on-farm trials. Except for winter rape grown on non-calcareous soils and maize grown in pot experiment, the shoot N/S ratio correlated more significantly with S-M3 compared to S-water and S-AEM.

Reducing topsoil depth decreases the yield and nutrient uptake of maize and soybean grown in a glacial till

AbstractSoil erosion decreases topsoil depth on hill slopes and increases depth in depositional areas, and hence impacts soil fertility and crop productivity in agricultural systems. However, it is not clearly elucidated how different crop species adapt to soil erosion regarding root function, nutrient uptake, and rhizosphere biochemical properties, which is pivotal to cropping strategy. We established three simulated erosion severities with topsoil depths of 10, 20, and 30 cm on a Mollisol farmland under a maize‐soybean rotation system with no‐tillage (zero‐tillage). After three consecutive years of field experiment, the decrease in topsoil thickness from 30 to 10 cm resulted in 9–22% decrease in maize yield but no impact on soybean yield. Compared to the 30‐ and 20‐cm topsoil thickness, the 10‐cm topsoil significantly lowered root and shoot biomass of maize at the jointing (V7) and milk stages (R3) and of soybean at the mid‐seed filling stage (R6). Compared to the 30‐cm topsoil treatment, the 10‐cm topsoil decreased available N and P in soil by 42 and 36% under maize, and by 25 and 19% under soybean, respectively, while the shallow topsoil also decreased ratios of N, P, and K content to root length with the decreases being less for maize than soybean. Compared to the 30‐cm topsoil depth, the 10‐ and 20‐cm topsoil significantly increased the activities of urease, phosphatase, and invertase in maize rhizosphere soil, but not in soybean rhizosphere soil except for the activity of urease in 10‐cm topsoil. These results indicated that maize was more sensitive to thinning of topsoil than soybean due to the reduced soil nutrient availability and its capability to extract nutrients from the soil. The greater stimulation of nutrient mineralization processes in soil did not alleviate the nutrient constraint to maize yield under shallow topsoil conditions. Thus, it is increasingly important to develop fertilization strategy to maintain nutrient supply for maize rather than soybean when these crops are grown in the shallow topsoil.

The crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa

Conservation agriculture has been promoted to sustainably intensify food production in smallholder farming systems in southern Africa. However, farmers have rarely fully implemented all its components, resulting in different combinations of no-tillage, crop rotation, and permanent soil cover being practiced, thus resulting in variable yield responses depending on climatic and soil conditions. Therefore, it is crucial to assess the effect of conservation agriculture components on yield stability. We hypothesized that the use of all three conservation agriculture components would perform the best, resulting in more stable production in all environments. We evaluated at, eight trial locations across southern Africa, how partial and full implementation of these components affected crop yield and yield stability compared with conventional tillage alone or combined with mulching and/or crop rotation. Grain yield and shoot biomass of maize and cowpea were recorded along with precipitation for 2 to 5 years. Across different environments, the addition of crop rotation and mulch to no-tillage increased maize grain by 6%, and the same practices added to conventional tillage led to 13% yield increase. Conversely, adding only mulch or crop rotation to no-tillage or conventional tillage led to lower or equal maize yield. Stability analyses based on Shukla’s index showed for the first time that the most stable systems are those in which mulch is added without crop rotation. Moreover, the highest yielding systems were the least stable. Finally, additive main effects and multiplicative interaction analysis allowed clarifying that mulch added to no-tillage gives stable yields on sandy soil with high rainfall. Similarly, mulch added to conventional tillage gives stable yield on sandy soil, but under low rainfall. This is the first study that highlighted the crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa, supporting their adaptability to climate change.

Validation and use of critical phosphorus concentration in maize

Abstract Plant-based indicators may have the potential to improve fertilizer phosphorus (P) recommendations for maize (Zea mays L.). Our objectives were (i) to validate existing models of critical P concentration (Pc) in maize shoot biomass during vegetative growth and (ii) to evaluate on farm the ability of the P nutrition index (PNI), a plant-based indicator derived from Pc, to predict a positive response to P fertilization. Existing models of Pc for maize were validated in a 3-yr experiment in which mineral fertilizer P was band-applied at planting at four rates (0, 10, 20, and 40 kg P ha−1) on a clay soil with a low to medium-low available-P content based on the soil P saturation index (PM-III/AlM-III). Fertilizer P generally did not affect shoot growth from the V6 to VT stages and grain yield, indicating that nonlimiting P conditions were achieved with no applied P. Critical P concentration under those nonlimiting P conditions was described by a linear function of shoot N concentration (Pc = 0.82 + 0.097 × N, R2 = 0.90), which was close to that previously reported in the same region (Pc = 1.00 + 0.094 × N). The on-farm PNI evaluation was conducted on eight farm sites varying in soil PM-III/AlM-III (0.021−0.308). Five P rates (0, 4.5, 9.0, 17.5, and 35.0 kg P ha−1) were applied on fields where the PNI had been measured the year before. The PNI at the V12 stage measured the year before was a better predictor of the relative grain yield with no P applied than the soil PM-III/AlM-III measured prior to planting. A critical PNI value of 0.9 was established below which a positive response to P fertilization is expected. This plant-based diagnostic approach therefore appears to be a valuable alternative or a complement to the currently used soil P test to decide whether fertilizer P is needed or not for maize production.

Nitrogen and sulfur interaction on nutrient use efficiencies and diagnostic tools in maize

Abstract Nitrogen (N) and sulfur (S) critical dilution curves and the N:S stoichiometry are useful tools for evaluating nutrient status in maize (Zea mays L.). Nutrient supply for both N and S impact plant nutrient uptake, consequently influencing the overall performance of fertilization diagnostic tools. Interaction between these nutrients has not been studied relative to their nutrient use efficiencies (NUE and SUE), agronomic efficiencies (NAE and SAE), and components of these. The aim of this study was to analyze the effect of N and S fertilization on: i) N and S uptake (NU and SU) dynamics, ii) N and S dilution curves, iii) N:S stoichiometry, and iv) NUE, SUE, NAE, SAE, and their components in maize. Five maize field trials were conducted evaluating the effect of N and S fertilization with two levels for each nutrient (unfertilized and fertilized). Maize shoot biomass and its N and S concentrations were measured from six-leaf to physiological maturity. The main outcomes of this study were: i) averaged across sites, N fertilization increased yield by 41% and S fertilization by 10%; ii) SU was delayed relative to NU; iii) S fertilization increased shoot S concentration when N was not limiting; iv) N dilution curve was not affected by S supply; v) N:S ratio decreased with increasing shoot biomass and varied with N and S supply; vi) N fertilization improved SUE and SAE via greater S recovery, with a similar S fertilization effect on NUE and NAE. This study demonstrated that both the critical S dilution curve and N:S stoichiometry are useful tools to characterize S status when N is not deficient. Simultaneous N and S management is critical for increasing their use efficiencies, improving crop productivity, and reducing environmental footprint.

Soil phosphorus availability modifies the relationship between AM fungal diversity and mycorrhizal benefits to maize in an agricultural soil

Arbuscular mycorrhizal (AM) fungi are very abundant in many agricultural soils and are important in increasing and maintaining the sustainability of agricultural systems. However, high soil fertility, especially high available soil phosphorus (P) status, often limits AM fungal development in intensively managed agricultural systems and results in the C-costs to the host plant outweighing any benefits from AM colonization. Some promising approaches can minimize negative effects on soil biota while providing the desired agricultural benefits (e.g. reduced soil tillage and organic amendments). However, the influence of these agricultural practices on the benefits of root mutualistic associations remains poorly understood. Here, we collected indigenous AM fungi from a long-term field experiment with different application rates of cow manure and conducted a pot experiment with different soil P levels. Using high throughput sequencing we demonstrate that increasing cow manure application changed the community composition of AM fungi and reduced community diversity in the field. Phosphorus addition in a bioassay experiment produced a mycorrhizal growth response (MGR) and the mycorrhizal P response (MPR) shifted from positive to negative, regardless of the origin of the inoculum. An increase in intraradical and extraradical AM fungal structures enhanced maize shoot biomass and P uptake under low (no P added) and moderate (20 mg P added kg−1 soil) P levels but the opposite occurred at a high P level (250 mg P added kg−1 soil). The MGR was higher in the treatment with higher community diversity at the moderate P level but there was no significant correlation at the other two P levels examined. We conclude that available soil P may regulate the abundance and diversity of AM fungi and their symbiotic function in intensive cropping systems. Our results indicate that managing the soil phosphorus level to favor a rich and diverse AM fungal community can enhance crop production and result in a more sustainable agricultural system.

Maize (Zea mays L.) Growth and Yield Response to Tillage Methods and Fertilizer Combinations in the Midland Agro-ecological Zones of Kenya

The trials were set up in Busia, Embu and Kirinyaga Counties to assess the effect of tillage methods and application of different fertilizer combinations on maize productivity in the lower and upper midland agro-ecological zones of Kenya. Tillage methods were no-tillage (NT) with crop residue retention as mulch (+CR) (NT+CR) and conventional tillage (CT) without crop residue retention on farm surface (-CR) (CT-CR) while fertilizer combinations were NK, NP, PK, NPK, and NPK+CaMgZnBS. The N, P, K, Ca, Mg, Zn, B and S nutrients were applied at the rates of 120, 40, 40, 10, 10, 5 and 26.3 kg ha-1, respectively. The trials were laid in a randomized complete block design with a split-plot arrangement and replicated three times. The results showed that maize leaf area index, plant height, aboveground biomass, crop growth rate, and grain yield were significantly higher under CT-CR than under NT+CR in most of the sites. The CT-CR system out-yielded NT+CR system by 0.3 t ha-1 and 0.6 t ha-1 maize grain in Alupe and Kirinyaga, respectively. However, NT+CR system out-yielded CT-CR system by 0.4 t ha -1 maize grain at Embu. Across all the sites, application of PK and NPK+ZnBMgCaS fertilizer combinations resulted, respectively, in lowest and highest maize shoot biomass, leaf area indices, crop growth rates, plant heights, and grain yields. Based on this result alone, the potential of conservation agriculture in improving yields compared to conventional tillage could not be conclusive despite consistently recording higher soil moisture content across all sites and better yields in Embu. Again, application of a wide range of nutrients may be beneficial to maize production in the study areas as evidenced in the study. Therefore, we recommend multi-season and multi-location trials to comprehensively assess the impact of tillage methods and fertilizer management, particularly in relation to micronutrients.

Improved phosphorus fertilisation efficiency of wood ash by fungal strains Penicillium sp. PK112 and Trichoderma harzianum OMG08 on acidic soil

Effective recycling of phosphorus (P) remains a critical issue in sustainable agriculture. Wood ash represents valuable soil amendment and potential source of P for agriculture, but its solubility and subsequent P-fertilisation efficiency is extremely low. This study tested fungal inoculants (Penicillium sp. PK112 and Trichoderma harzianum OMG08) applied alone and in combination with wood ash on P-limiting acidic soil to determine if they can improve P-nutrition in maize. Wood ash alone did not have any significant P-fertilising effect. Application of both inoculants, when combined with wood ash, led to significant increment of plant-available P content in soil, increased P uptake by maize plants and consequently to higher production of maize shoot biomass. Both inoculants suppressed overall microbial activity in soil as determined by the activity of dehydrogenase, alkaline phosphatase and microbial P content. Only T. harzianum led to higher activity of soil acid phosphatase. This study demonstrated that tested strains may be co-applied with wood ash to improve its P-fertilisation efficiency. The positive influence of inoculants on P availability was mainly due to stronger acidification of rhizosphere and decreased content of microbial P. However, both effects seemed to be hindered by the P sorption capacity of the soil in the case of inoculation without wood ash. Such findings may lead to development of novel formulations of recycled fertiliser products and boost nutrient recycling in agriculture.

Mechanical and Hydric Stress Effects on Maize Root System Development at Different Soil Compaction Levels.

Soil mechanical resistance, aeration, and water availability directly affect plant root growth. The objective of this work was to identify the contribution of mechanical and hydric stresses on maize root elongation, by modeling root growth while taking the dynamics of these stresses in an Oxisol into consideration. The maize crop was cultivated under four compaction levels (soil chiseling, no-tillage system, areas trafficked by a tractor, and trafficked by a harvester), and we present a new model, which allows to distinguish between mechanical and hydric stresses. Root length density profiles, soil bulk density, and soil water retention curves were determined for four compaction levels up to 50 cm in depth. Furthermore, grain yield and shoot biomass of maize were quantified. The new model described the mechanical and hydric stresses during maize growth with field data for the first time in maize crop. Simulations of root length density in 1D and 2D showed adequate agreement with the values measured under field conditions. Simulation makes it possible to identify the interaction between the soil physical conditions and maize root growth. Compared to the no-tillage system, grain yield was reduced due to compaction caused by harvester traffic and by soil chiseling. The root growth was reduced by the occurrence of mechanical and hydric stresses during the crop cycle, the principal stresses were mechanical in origin for areas with agricultural traffic, and water based in areas with soil chiseling. Including mechanical and hydric stresses in root growth models can help to predict future scenarios, and coupling soil biophysical models with weather, soil, and crop responses will help to improve agricultural management.

Neighbouring plants modify maize root foraging for phosphorus: coupling nutrients and neighbours for improved nutrient-use efficiency.

Nutrient distribution and neighbours can impact plant growth, but how neighbours shape root-foraging strategy for nutrients is unclear. Here, we explore new patterns of plant foraging for nutrients as affected by neighbours to improve nutrient acquisition. Maize (Zea mays) was grown alone (maize), or with maize (maize/maize) or faba bean (Vicia faba) (maize/faba bean) as a neighbour on one side and with or without a phosphorus (P)-rich zone on the other in a rhizo-box experiment. Maize demonstrated root avoidance in maize/maize, with reduced root growth in 'shared' soil, and increased growth away from its neighbours. Conversely, maize proliferated roots in the proximity of neighbouring faba bean roots that had greater P availability in the rhizosphere (as a result of citrate and acid phosphatase exudation) compared with maize roots. Maize proliferated more roots, but spent less time to reach, and grow out of, the P patches away from neighbours in the maize/maize than in the maize/faba bean experiment. Maize shoot biomass and P uptake were greater in the heterogeneous P treatment with maize/faba bean than with maize/maize system. The foraging strategy of maize roots is an integrated function of heterogeneous distribution of nutrients and neighbouring plants, thus improving nutrient acquisition and maize growth. Understanding the foraging patterns is critical for optimizing nutrient management in crops.

Early priority effects of occupying a nutrient patch do not influence final maize growth in intensive cropping systems

Priority effects can be caused by an individual plant within a population that is the first to occupy and explore nutrient patches. However, the magnitude of priority effects of exploring a nutrient patch on plant growth during the ontogeny remains obscure. A 30-day rhizo-box experiment and a 2-year field trial with maize (Zea mays L) were conducted to examine the influence of priority effects arising from heterogeneous nutrient (nitrogen and phosphorus) supply on the root and shoot growth of maize under nutrient-limited and nutrient-rich environments. In the rhizo-box with limited soil resources, maize shoot biomass and nutrient content increased with the closeness to the nutrient patch, suggesting strong priority effects. In the field trial with high fertilizer input, priority effects arising from root proliferation within the nutrient patch also brought growth advantages for individual plants close to the patch in the first 45 days after sowing (DAS), but positive effects were weaker than in rhizo-box conditions. The growth advantage was not maintained after 60 DAS. The early priority effects did not promote grain yield. Our findings demonstrated that the growth advantage of early priority effects from exploring the nutrient patch was dependent on time and soil nutrient supply.

Effects of poultry manure on soil infiltration, organic matter contents and maize performance on two contrasting degraded alfisols in southwestern Nigeria

PurposeThis research work described the effect of organic waste (poultry manure) on soil cumulative infiltration rate (CIR), soil organic matter (SOM), and maize performance on two contrasting alfisols of southwestern Nigeria.MethodsSix treatments of poultry manure were applied in split at 0 Mg/ha, 2 Mg/ha, 4 Mg/ha, 6 Mg/ha, 8 Mg/ha, and 10 Mg/ha, in replicate under a completely randomized design to clay loam (CL) and sandy clay loam (SCL) soils, at 3, 6, 9, and 12 weeks after the initial application.ResultsThe results showed significant increases (P < 0.05) in CIR, SOM, and maize performance compared to the control in both soils. Poultry manure at 10 Mg/ha recorded the highest SOM which was significantly (P < 0.05) different from other application rates in both soils. The mean values for SOM in SCL were between 0.67 and 3.75% for 0 Mg/ha and 10 Mg/ha, while the mean values recorded for CL were between 0.80 and 4.35% at 0 Mg/ha and 10 Mg/ha. Poultry manure reduced CIR in the SCL, but improved CIR with increasing rates on CL. Poultry manure at 4–10 Mg/ha increased the maize shoot biomass significantly (P < 0.05). However, the application rate of 6 Mg/ha manure recorded the highest fresh shoot biomass, while 8 Mg/ha increased dry shoot biomass in both soils.ConclusionThis study indicated that poultry manure applied at 10 Mg/ha gave the best results in improving CIR, SOM, and maize performance on different soil types.