Increased Maize Yield Research Articles

Enhanced maize yield and water-use efficiency via film mulched ridge–furrow tillage with straw incorporation in semiarid regions

ABSTRACT Film mulched ridge-furrow tillage (FMRF) with straw incorporation (S) can efficiently improve rain-fed maize yield and water use efficiency (WUE). The key mechanisms were investigated via a 3-year consecutive FMRF and S interactive experiments [CP (conventional planting, Control), CPS, FMRF, FMRFS] from 2014 to 2016. In comparison with CP, FMRFS increased the temperature by 1.8°C to 4.8°C and the soil water content of 0–200 cm soil profile (W200 ) by 98.0 mm to 106.7 mm from the seedling to tasseling stage, and decreased the temperature by 1.1°C to 3.7°C from flowering to maturity. The concentrations of soil organic carbon (SOC), soil total and available nitrogen, phosphorus and potassium (TN, TP, TK and AN, AP, AK) were also remarkable increased by 5.9% to 55.1% (P < 0.05) for FMRFS, respectively. FMRFS considerably mitigated the effects of the frequent water and heat stress and fertility deficit and led to a higher maize yield (27.0% to 40.0%), improved WUE (1.4-folds to 2.0-folds). The W200 , SOC, TN, TP, AN and AP significant contribute to maize yield. Therefore, FMRFS not only enhanced the soil fertility but also maintained soil water balance, thus causing a significant increase in maize yield and WUE.

Maize-Brachiaria intercropping: A strategy to supply recycled N to maize and reduce soil N2O emissions?

Nitrogen use in agriculture directly impacts food security, global warming, and environmental degradation. Forage grasses intercropped with maize produce feed for animals and or mulch for no-till systems. Forage grasses may exude nitrification inhibitors. It was hypothesized that brachiaria intercropping increases N recycling and maize grain yield and reduces nitrous oxide (N2O) emissions from soil under maize cropping. A field experiment was set up in December 2016 to test three cropping system (maize monocropped, maize intercropped with Brachiaria brizantha or with B. humidicola) and two N rates (0 or 150 kg ha-1). The grasses were sown with maize, but B. humidicola did not germinate well in the first year. B. brizantha developed slowly during the maize cycle because of shading but expanded after maize was harvested. The experiment was repeated in 2017/2018 when B. humidicola was replanted. N2O and carbon dioxide (CO2) emissions, maize grain yield and N content were measured during the two seasons. After the first maize harvest, the above- and below-ground biomass, C and N content of B. brizantha grown during fall-winter, and the biological nitrification inhibition potential of B. brizantha were evaluated. Maize yield responded to N fertilization (5.1 vs. 9.8 t ha-1) but not to brachiaria intercropping. B. brizantha recycled approximately 140 kg N ha-1 and left 12 t dry matter ha-1 for the second maize crop. However, the 2017/18 maize yields were not affected by the N recycled by B. brizantha, whereas N2O emissions were higher in the plots with brachiaria, suggesting that part of the recycled N was released too early after desiccation. Brachiarias showed no evidence of causing nitrification inhibition. The strategy of intercropping brachiarias did not increase maize yield, although it added C and recycled N in the system.

Improving photosynthesis to increase grain yield potential: an analysis of maize hybrids released in different years in China

In this work, we sought to understand how breeding has affected photosynthesis and to identify key photosynthetic indices that are important for increasing maize yield in the field. Our 2-year (2017–2018) field experiment used five high-yielding hybrid maize cultivars (generated in the 1970s, 2000s, and 2010s) and was conducted in the Xinjiang Autonomous Region of China. We investigated the effects of planting density on maize grain yield, photosynthetic parameters, respiration, and chlorophyll content, under three planting density regimens: 75,000, 105,000, and 135,000 plants ha−1. Our results showed that increasing planting density to the medium level (105,000 plants ha−1) significantly increased grain yield (Y) up to 20.32% compared to the low level (75,000 plants ha−1). However, further increasing planting density to 135,000 plants ha−1 did not lead to an additional increase in yield, with some cultivars actually exhibiting an opposite trend. Interestingly, no significant changes in photosynthetic rate, dark respiration, stomatal density, and aperture were observed upon increasing planting density. Moreover, our experiments revealed a positive correlation between grain yield and the net photosynthetic rate (Pn) upon the hybrid release year. Compared to other cultivars, the higher grain yield obtained in DH618 resulted from a higher 1000-kernel weight (TKW), which can be explained by a longer photosynthetic duration, a higher chlorophyll content, and a lower ratio of chlorophyll a/b. Moreover, we found that a higher leaf area per plant and the leaf area index (HI) do not necessarily result in an improvement in maize yield. Taken together, we demonstrated that higher photosynthetic capacity, longer photosynthetic duration, suitable LAI, and higher chlorophyll content with lower chlorophyll a/b ratio are important factors for obtaining high-yielding maize cultivars and can be used for the improvement of maize crop yield.

Dry matter accumulation after silking and kernel weight are the key factors for increasing maize yield and water use efficiency

Reducing use of irrigation water and improving crop yield are important since water shortage and food security are the two main problems in developing sustainable agriculture. In this study, we aim to reduce the conventional irrigation amount and to determine the mechanisms for yield formation and water use efficiency (WUE) increasing, and to identify the optimal irrigation amount for high yield maize (> 15 Mg ha–1) under mulch drip irrigation in arid, semi-arid, and semi-humid areas. Experiments carried out in the arid area (Changji), semi-arid area (Qitai), and semi-humid area (Xinyuan) in 2018 and 2019 showed that the optimal irrigation amount was 720 mm, 540 mm, and 180 mm, respectively. As compared to the irrigation amount used by farmers irrigation amount (maximum irrigation amount), the optimal irrigation amount recorded in our study could save 11.1–60.0% of water. At the same time, the WUE and irrigation water use efficiency (IWUE) increased by 5.2–60.3% and 7.9–181.6% with maize yield > 15 Mg ha–1. Less than optimal irrigation, increasing yield and WUE by increasing both dry matter accumulation after silking (DMA) and thousand kernel weight (TKW). Over optimal irrigation, the yield further increased mainly by increasing dry matter at maturity, and increasing WUE by kernel number per ear. The most photosynthate was transferred from leaves and stems to grains in minimum irrigation, but the lowest that in maximum irrigation. Therefore, DMA and TKW are the key factors to increase yield and WUE under less than optimal irrigation. Optimize irrigation goal may be to improve the transport of photosynthate to grain in the future.

K-Domain Technology: Constitutive Expression of a Blueberry Keratin-Like Domain Mimics Expression of Multiple MADS-Box Genes in Enhancing Maize Grain Yield.

MADS-box genes are considered as the foundation of all agronomic traits because they play essential roles in almost every aspect of plant reproductive development. Keratin-like (K) domain is a conserved protein domain of tens of MIKC-type MADS-box genes in plants. K-domain technology constitutively expresses a K-domain to mimic expression of the K-domains of other MADS-box genes simultaneously and thus to generate new opportunities for yield enhancement, because the increased K-domains can likely prevent MADS-domain proteins from binding to target DNA. In this study, we evaluated utilizing the K-domain technology to increase maize yield. The K-domain of a blueberry’s SUPPRESSOR of CONSTITUTIVE EXPRESSION OF CONSTANS 1 (VcSOC1K) has similarities to five MADS-box genes in maize. Transgenic maize plants expressing the VcSOC1K showed 13–100% of more grain per plant than the nontransgenic plants in all five experiments conducted under different experimental conditions. Transcriptome comparisons revealed 982 differentially expressed genes (DEGs) in the leaves from 83-day old plants, supporting that the K-domain technology were powerful and multiple functional. The results demonstrated that constitutive expression of the VcSOC1K was very effective to enhance maize grain production. With the potential of mimicking the K-domains of multiple MADS-box genes, the K-domain technology opens a new approach to increase crop yield.

Increasing maize yields in Northeast China are more closely associated with changes in crop timing than with climate warming

An understanding of mechanisms that underlie the steady increase in crop yields over recent decades is important for promotion of future sustainable yield gains and maintenance of future food security. In this study, we coupled observational maize yield and climate variables based on crop development data from 1981 to 2009 to construct an empirical model that can resolve the separate and combined effects of climate and agricultural practices related to crop timing on maize yield in Northeast China (NEC), the largest spring maize-producing region of China. Climate warming contributed to approximately 15.6% of the trend for increasing yield over the 29 year period. The beneficial effects of climate warming on yield were due to increases in accumulation of temperatures between 10 °C and 30 °C (growing degree days, GDD), which positively contributed to 29.7% of yield and offset the −14.1% yield reduction caused by a trend involving increasing accumulation of temperatures above 30 °C (or extreme degree days, EDD). Adaptive improvements in crop timing practices (e.g. shifts in planting date and selection of later-maturity cultivars) further optimized the impacts of GDD and EDD during the entire growing season by exploiting more GDD during the reproductive phase and fewer EDD during the vegetative phase, thereby contributing to a yield gain of 25.4% over the period from 1981 to 2009. Taken together, climate warming and crop timing practices contributed to 39.4% of the maize yield increase since 1981. Yield losses due to climate warming were detected at only one site located in the southern part of the NEC region, where yield losses must be offset by positive effects of crop timing changes. The trends in maize yields presented here may provide guidance for effective adaptation options for maize production under conditions of continued climate warming.

Straw incorporation with ridge–furrow plastic film mulch alters soil fungal community and increases maize yield in a semiarid region of China

The Loess Plateau is a typical dry farming area in China. Film mulching—a widely used practice in this region—can be further deplete the poor soil organic matter levels. Straw incorporation can alleviate the adverse environmental impact of film mulching and increase crop yield. However, few studies have investigated the effects of continuous straw incorporation with film mulching on the soil fungal community in the Loess Plateau of China. This study compared the effects of straw incorporation (S) and without straw incorporation (NS) under ridge–furrow plastic film mulch on fungal community structure, fungal network structure, soil quality, and maize yield in a four-year experiment. At the end of the experiment, the soil under S had greater soil fungal richness than the soil under NS. The fungal community had greater stability and complexity and more competition and cooperation between fungi under S than NS. The stochastic process played a stronger role in constructing the fungal community under NS than S. Continuous straw incorporation changed the key dominant species from Agaricomycetes, Dothideomycetes, and Leotiomycetes under NS to Ascomycetes under S. The pathogenic fungal population significantly increased by 166% under S. Changes in the soil fungal community under S were mainly affected by increasing soil moisture, total phosphorus, and total nitrogen. Continuous straw incorporation improved soil quality with increased soil urease and catalase activities and soil organic carbon and available phosphorus contents. In four years, S significantly increased the maize yield by 4–15% compared with NS treatment. In sum, continuous straw incorporation changed the fungal community composition, improved the relationships between fungal communities and soil quality, contributing to the increased maize yield under S. The results of this study could promote the sustainable development of agriculture, which has great significance for the wider application of straw incorporation in China and elsewhere.

Maize Seedling Establishment, Grain Yield and Crop Water Productivity Response to Seed Priming and Irrigation Management in a Mediterranean Arid Environment

Water shortage is a major environmental stress that destructively impacts maize production, particularly in arid regions. Therefore, improving irrigation management and increasing productivity per unit of water applied are needed, especially under the rising temperature and precipitation fluctuations induced by climate change. Laboratory and field trials were carried out in the present study, which were aimed at assessing the possibility of promoting maize germination, growth, grain yield and crop water productivity (CWP) using seed priming under different irrigation regimes. Two seed priming treatments, i.e., hydro-priming and hardening versus unprimed seeds, were applied under four irrigation regimes, i.e., 120, 100, 80 and 60% of estimated crop evapotranspiration (ETc). The obtained results indicated that increasing irrigation water from 100% up to 120% ETc did not significantly increase grain yield or contributing traits, while it decreased CWP. Deficit irrigation of 80 and 60% ETc gradually decreased grain yield and all attributed traits. Seed priming significantly ameliorated seedlings’ vigor as indicated by earlier germination, higher germination percentage, longer roots and shoots, and heavier fresh and dry weight than unprimed seeds with the superiority of hardening treatment. Additionally, under field conditions, seed priming significantly increased grain yield, yield contributing traits and CWP compared with unprimed treatment. Interestingly, the results reflect the role of seed priming, particularly hardening, in mitigating negative impacts of drought stress and enhancing maize growth, grain yield and attributed traits as well as CWP under deficit irrigation conditions. This was demonstrated by a significant increase in grain yield and CWP under moderate drought and severe drought conditions compared with unprimed treatment. These results highlight that efficient irrigation management and seed priming can increase maize yield and water productivity in arid environments.

Responses of maize yield, nitrogen and phosphorus runoff losses and soil properties to biochar and organic fertilizer application in a light-loamy fluvo-aquic soil

Nitrogen (N) and phosphorus (P) are the primary nutrients to the promoting of crop yield, however, the losses of N and P by runoff dominated the non-point pollution. In the context of maintaining high farmland productivity and mitigating negative impacts on the environment, it is important to understand how biochar and organic fertilizer application influence maize yield, N and P use efficiency and losses by runoff, as well as soil quality. To address this, the current study was conducted based on a three-year field experiment that includes five fertilized treatments: No fertilizer (CK), chemical fertilizer (CF), CF + biochar (CFB), 20% chemical N was replaced by organic fertilizer (OF) and OF + biochar (OFB). The amendments of biochar and organic fertilizer significantly increased maize yield, N and P use efficiency, and meanwhile, decreased the N and P losses by runoff. From 2017 to 2019, the yield of OFB treatment was 4.4–161.9% higher than that of other treatments, The N and P use efficiencies of OFB treatment was 3.0–83.7% and 9.9–195.1% higher than that of other treatments respectively. N losses by runoff were decreased by 35.1–59.7% in OFB than CF, and −0.6–42.0% in OFB than other fertilized treatments. P losses by runoff were decreased by 39.9–48.8% in OFB than CF, and 5.6–32.0% in OFB than other fertilized treatments in 2018 and 2019. Moreover, biochar amendment significantly improved soil aggregate stability, and increased extracellular urease and acid phosphatase activities. Soil alkaline hydrolysable nitrogen and available potassium contents were significantly increased by the biochar amendment, but no significant impact on soil available P. These findings indicate that the integrated use of chemical fertilizer, organic fertilizer and biochar has the potential to maintain high grain yield with mitigating environmental impact.

Phenological synchrony between summer maize and the Asiancorn borer

<p indent=0mm>Maize is one of China’s main food crops, and its growth and yield are significantly influenced by climate change, diseases, and insect pests. Phenological synchrony describes the matching extent of different phenological events. As an important indicator representing species interaction, phenological synchrony plays a vital role in directing agricultural production. In natural ecosystems, two mechanisms can be applied to explain the phenological mismatch between interacting species. On the one hand, there are differences in the rate of development for different species responding to a change of environmental factors; on the other hand, species evolve to better adapt to the changed environment after the asynchrony. The phenological synchrony between summer maize and the Asian corn borer has currently received less attention. Using the data of summer maize phenology, the adult peak of the Asian corn borer, and meteorological records at three stations in Heze city over the past <sc>18 years</sc> (1995–2012), the results show that summer maize phenology has a legacy effect. The controlled sowing date indirectly changes the jointing date and tasseling date, which ultimately causes the nonlinear trend of the synchrony between jointing and tasseling dates and the adult peak of the Asian corn borer. There is no significant synchrony change between the milking date and the second adult peak over the study period. The controlled sowing date largely changes the occurrence of the Asian corn borer during summer maize development, which may affect the corn borer’s population, and finally changes maize yield. To control pests, increase maize yield and actively deal with climate change, it is vital to deeply study the mechanism of the change of phenological synchrony between maize and the Asian corn borer under the effect of human-controlled sowing date and climate change.

Subsidies and the African Green Revolution: Direct Effects and Social Network Spillovers of Randomized Input Subsidies in Mozambique

The Green Revolution, which bolstered agricultural yields and economic well-being in Asia and Latin America beginning in the 1960s, largely bypassed sub-Saharan Africa. We study the first randomized controlled trial of a government-implemented input subsidy program (ISP) in Africa intended to foment a Green Revolution. We find that this temporary subsidy for Mozambican maize farmers stimulates Green Revolution technology adoption and leads to increased maize yields. Effects of the subsidy persist in later unsubsidized years. In addition, social networks of subsidized farmers benefit from spillovers, experiencing increases in technology adoption, yields, and beliefs about the returns to the technologies. Spillovers account for the vast majority of subsidy-induced gains. ISPs alleviate informational market failures, stimulating learning about new technologies by subsidy recipients and their social networks. (JEL O13, Q12, Q16, Q18)

Dual Functional Coatings for Urea to Reduce Ammonia Volatilization and Improve Nutrients Use Efficiency in a Brazilian Corn Crop System

The investigation aimed to evaluate the use of micronutrients Zn, B, and the urease inhibitor (N-(n-butyl) thiophosphoric triamide) (NBPT), associated with an organic polymer to reduce ammonia losses (N-NH3) and increase maize yield. Two experiments were conducted under field conditions in Luminarias and Ingai, Minas Gerais, Brazil. The treatments consisted of the application of prilled urea, urea coated by an organic polymer, polymer + zinc (Zn), and boron (B) or NBPT, which are urease inhibitors in the soil, and a control treatment without N application. The reduction of N-NH3 losses applying the studied sources ranged between 0.2 and 42% on average. Leaf N concentration at flowering varied between 21 and 27 g kg−1, Zn concentration varied between 34 and 38 mg kg−1, and grain yield ranged from 3403 to 4810 kg ha−1. Grain yield increased by 15% on average compared to the control treatment. The addition of the organic polymer alone to urea reduces N losses by volatilization compared to prilled urea. However, when associated with Zn and B additions, this approach becomes more effective. The NBPT (N-(n-butyl) thiophosphoric triamide) concentrations used in this study exhibited low efficiencies in reducing N losses by volatilization. The application of Zn and B with the organic polymer affected nutrient uptake at the maize flowering stage but was not enough to increase maize yield. The removal of Zn and B by the grains was enhanced by the addition of these micronutrients to the organic polymer coating, regardless of the Zn source.

Ameliorative Effects of Calcium Sprays on Yield and Grain Nutritional Composition of Maize (Zea mays L.) Cultivars under Drought Stress

Drought stress is seriously affecting maize production. To investigate the influence of calcium (Ca) foliar application on maize production and chemical composition of grains under drought stress, two experiments were carried out at Cairo University Research Station, Giza, Egypt, during the summer seasons of 2018 and 2019. The experimental design was split-split plot design with a completely randomized blocks arrangement with three replications. Water regimes were assigned to the main plots [100 (control), 75, and 50% of estimated evapotranspiration]. Calcium levels (zero and 50 mg/L) were assigned to the sub plots. Maize cultivars (SC-P3444, Sammaz-35 and EVDT) were assigned to the sub-sub plots. Three maize cultivars were sprayed with Ca solution concentration (50 mg/L) under normal and drought conditions. The control treatment (0 mg/L) was sprayed with an equal amount of distilled water for comparison. Results indicated a significant decrease in total yield and grain characteristics [protein, ash, total sugars, nitrogen (N), phosphorus (P), potassium (K), and iron (Fe) contents] as a response of drought. Calcium foliar application significantly increased maize yield, protein, ash, carbohydrates, starch, total sugars, and ionic contents of grains, except for manganese (Mn), under all irrigation levels. Based on the drought tolerance index (DTI), only cultivar SC-P3444 showed drought tolerance while cultivars Sammaz-35 and EVDT were sensitive to drought stress. Foliar application of Ca on SC-P3444 cultivar achieved the highest grain yield per hectare (8061 kg) under the water regime of 100% of the total evapotranspiration, followed by Sammaz-35 (7570 kg), and EVDT (7191 kg) cultivars. At the water regime of 75% of estimated evapotranspiration (75% irrigation), Ca foliar application increased grain yield by 16, 13 and 14% in SC-P3444, Sammaz-35, and EVDT, respectively. At the water regime of 50% of the estimated evapotranspiration (50% irrigation), Ca foliar application increased grain yield by 17, 16, and 13% in SC-P3444, Sammaz-35, and EVDT, respectively. In brief, Ca had a clear impact on productivity and grain quality with important implications for maize yield under normal and water stress conditions. Our findings demonstrate that foliar application of Ca enabled drought stressed maize plants to survive better under stress. The most water stress tolerant cultivar was SC-P3444 followed by Sammaz-35 and EVDT under drought stress.

Field Performance of Three-way Cross Yellow and White Maize Hybrids in Nepal

Maize hybrids can increase production, bridge the yield gap, and boost up domestic production in Nepal. Three-way cross hybrid introduces an alternative to produce low cost hybrid seed for resource poor farmers. A study was performed to identify promising yellow and white maize hybrids developed by International Centre for Maize and Wheat Improvement (CIMMYT), Mexico in Rampur, Nepal. Nineteen three-way cross white maize hybrids with two checks and seventeen yellow maize hybrids with one check were tested in field experiments on 2017 and 2018. Treatments were replicated twice in α-lattice design with each experimental plot of 9.6-m2 (4-m × 2.4-m). AF17A-426-13/14, AF17A-426-1/2, AF17A-426-28/39, and AF17A-426-15/16 were the three-way cross white hybrids produced grain yield of more than 9000 kg ha-1. Similarly, AF17A-473-20/29 and AF17A-473-18/27 yielded about 9000 kg ha-1 among the three-way cross yellow maize hybrids. These hybrids have commercial potentials to increase maize yield in Nepal if the provided parents are successful in the seed production.

Effect of spatial arrangement of push-pull companion plants on fall armyworm control and agronomic performance of two maize varieties in Ghana

Maize (Zea mays L.) production is constrained in Ghana by declining soil fertility, erratic rainfall and the recent fall armyworm invasion. We hypothesised that adopting push-pull farming practices would reduce infestation and damage of maize by fall armyworm, while increasing maize yield. We conducted field experiments at two sites over two cropping seasons to evaluate the effects of spatial arrangements of push-pull companion crops on fall armyworm infestations and grain yield of maize. The experiment was arranged in a split-plot design with variety (Abotem and Opeaburo) as the main plot and fall armyworm treatment options (1 row maize and 1 row Desmodium [conventional push-pull]; three maize rows before one row of Desmodium [modified push-pull]; synthetic chemical and no treatment [control]) as a subplot. Results showed that, regardless of location or maize variety, both conventional and spatially modified push-pull companion cropping significantly reduced fall armyworm infestations under all seasons, as compared with the control. The push-pull companion cropping systems reduced the mean maize damage score of fall armyworm by 168%, compared with the control. Additionally, both conventional and spatially modified push-pull companion cropping significantly increased maize grain and biomass yield by 46.80% and 51.11%, respectively, irrespective of the maize variety compared with the control. The mean damage score, biomass and grain yield of conventional push-pull and modified push-pull were not significantly different. The fall armyworm infestation was decreased by 14.61% in the major season compared with the minor cropping season. This study provides novel evidence of the effectiveness of push-pull farming practice in reducing fall armyworm infestation and damage, and in increasing maize yield in Ghana, which has a different ecosystem to East Africa, where push-pull was developed. Further, it provides critical evidence of the effectiveness of a spatial modification of the push crop in relation with the main crop against the fall armyworm.

Physiological and nutritional significance of potassium application under sole and intercropped maize (&lt;em&gt;Zea mays&lt;/em&gt; L.)

Highlights - Potassium nutrient management in maize-soybean strip intercropping can increase the resource use efficiency. - Compared to the T0 (no potassium), T2 (80 kg ha–1 on maize) application increases the light interception and leaf area index of maize by 17% and 38% respectively. - Regression analysis reveals a positive relationship between physiological parameters measured at R2 and at R6 growth stages in maize under maize-soybean strip intercropping. - High K2O (80 kg ha–1) inputs enhanced the partitioning of biomass production in maize. - Overall, the optimum K2O application increased the maize yield by 16% under maize-soybean strip intercropping system relative to control.&#x0D; &#x0D; Globally, maize is an essential food and fodder crop. Fertilisers, as soil amendments, particularly K2O, could increase maize yields. A Two-year field research was designed in 2018- 2019 to examine the influence of three-potassium fertiliser applications on maize-soybean strip intercropping and sole-maize yield components. A Randomized complete block design with three replications was used, and one of three K2O doses (T0, 0; T1, 40:30; T2, 80:60 kg ha–1) was given in each plot. The effects K2O treatments on photosynthetic characteristics, photosynthetic active radiation, leaf area index, total biomass accumulation, and seed yield were investigated at V6, R2, R4, and R6. Compared to T0, maize-soybean strip intercropping system and sole-maize results showed T2 maize enhanced the light interception by 14, 26, 15, and 17% at V6, R2, R4, and R6 respectively. Maize increased the partitioning of biomass to cob and seed by 8 and 10% at R6, respectively in T2, relative to T0 treatment. T2 showed a higher green leaf area than T0; K2O applications led to an enhancement in leaf area index at R6 by 38%, under T2, and subsequently increased the photosynthetic rate at R4 and R6 by 8% and 6% respectively, in both years of the study. These results suggest that we may increase the accumulation of biomass and the yield of the maize seed under maize-soybean strip intercropping system and sole-maize by optimum K application in maize plants.

Effects of Different Planting Patterns on the Growth and Yield of Maize and Soybean in Northwest China

Aboveground and belowground interactions are crucial in the over-yielding of intercropping systems. However, the relative effects of aboveground and belowground interactions on yields in maize (Zea mays L.) and soybean (Glycine max) intercropping systems are still unclear. Field experiments, including measurements of plant height, soil-plant analysis development (SPAD) value, photosynthetically active radiation (PAR), root length density (RLD), root volume density (RVD), and grain yield, were conducted in 2018-2019 to analyze the advantages and effects of above-ground and belowground inter-species interactions. This study adopted three different planting patterns: mono-cropping maize (MM), mono-cropping soybeans (MS), and maize-soybean intercropping (IM and IS). This study showed that intercropping promotes the growth of maize and makes maize have a better photosynthetic environment, while the growth of intercropping soybeans is inhibited and the photosynthetic environment becomes worse. In the upper layer (0-40 cm) and close to the plants, the root growth and distribution of intercropped maize increased, resulting in greater root length density and volume density, while the root growth and distribution of intercropped soybean decreased, resulting in lower root length density and volume density. The intercropping increased the maize yield by 18.52-19.8%, and reduced the soybean yield by 55.87-57.44%. The results indicated that intercropping improves the competitiveness of maize and reduces the competitiveness of soybeans. The increase in maize yield made up for the loss of soybean yield and led to an overall significant advantage in the maize-soybean intercropping system.

Influence of soil organic carbon, fertiliser management, and weeding regime on weed dynamics and maize productivity on sandy soils in eastern Zimbabwe

Labour bottlenecks and multiple operations at the start of a cropping season often result in inadequate early weed control and subsequent poor crop performance. Therefore, there is a need to establish management practices that provide the best opportunities for the gains associated with weeding and nutrient management across farms. We investigated the influence of soil organic carbon (SOC), fertiliser management, and weeding regimes on weed dynamics and maize productivity on smallholder farms with contrasting SOC in eastern Zimbabwe. On each site, and for two seasons, a 2 × 5 factorial experiment laid in a randomised complete block design was used. Fertiliser management was NPK or NPK + cattle manure (CM); weeding regimes were herbicide + hoe weeding, hoe weeding thrice/twice/once, or weedy check. Principal component analysis was used to evaluate weed density. The grain yield of maize increased by 13% on the sites with higher SOC. Integrating NPK + CM increased weed density and maize grain yield by 1.32 and 1.46-times, respectively, compared with NPK application only. The increased maize yield from fertiliser-managed treatments occurred only in early frequently weeded treatments. However, fertiliser application had little effect when weeding was delayed, as maize yield instead declined by 40–80%. We concluded that higher SOC increased weed density and weed biomass. Smallholder farmers are encouraged to combine herbicide application combined with hoe-weeding options for sustainable maize production.

Mungbean-maize rotation improved soil properties and maize yield in dryland

One of the conditions to improve maize yield in dryland areas is by improving soil properties. This paper reports on the improvement of soil properties and maize yield resulted from rotating mungbean and maize in two consecutive years. In the first year, mungbean was grown as a cover crop at different population densities (250,000, 375,000, and 500,000 plants ha−1) combined with desiccation times of 28 and 35 days after planting in April 2019. Two weeks after the desiccation, maize seeds were planted at a density of 9 plants per m2. In those cover crop plots and a control treatment without a cover crop. All the treatments were replicated three times and were arranged in a Randomized Block Design. Following the maize crops, mungbean was grown again (except in the control plots) from October to December 2019 at the same population densities as before, combined with two seed classes; stock seeds and extension seeds. The mungbean was harvested in mid-December 2019 and after biomass determination, the residue was incorporated into the treatment plots. In mid-January 2020, maize seeds were planted at the same population density as before in all plot treatments, including control plots. Soil properties were determined at 60 days after maize planting. The results revealed that nitrogen, phosphorous, and potassium in the soil increased substantially by 52.6, 282.9, and 110%, respectively after two years of the rotation. There was an average of 44.7% increase in maize yield resulted from the highest mungbean population density plots as compared to the control treatment. It is concluded that mungbean-maize rotation is an effective way to improve maize yield in dryland areas.

Integrated nitrogen amount and sources maximize maize nitrogen efficiency in the saline soils

AbstractAlthough efficient N fertilization has become widely accepted for sustaining or improving N use efficiency (NUE), many existing N fertilizer recommendations seldom consider N sources during implementation. To investigate the effect of N rates and sources on maize (Zea mays L.) production efficiency, soil quality, and economic benefits, a field experiment was conducted in the coastal saline area of China. The optimal N rate (ONR) treatment based on in‐season root‐zone N management reduced N application amount by 44% without grain yield losses and decreased the apparent N losses by 144 kg N ha–1 compared with the local N management practice of farmers. Furthermore, the ONR treatment with ammonium sulfate (ONR‐AS) or calcium ammonium nitrate (ONR‐CAN) had higher maize grain yield and NUE than the ONR with urea (ONR‐urea) treatment. Compared with ONR‐urea, treatment with ONR‐AS or ONR‐CAN increased Ca2+ content, decreased soil pH and Na+ content, and thus imporved maize yield and NUE. Among the ONR treatments, the ONR‐AS treatment increased economic gains compared with the ONR‐urea treatment. This study suggests that an integrated N management can increase maize yield, NUE, and economic benefits and improve soil quality in the coastal saline soils.