Unmulched Soil Research Articles

Field-grown lettuce production optimized through precision irrigation water management using soil moisture-based capacitance sensors and biodegradable soil mulching

AbstractScientists, environmentalists, and farmers are currently in pursuit of sustainable agricultural practices that can effectively ensure global food security while simultaneously mitigating environmental degradation. A field experiment was conducted to elucidate the impact of low-cost capacitance soil moisture-based sensors on lettuce (Lactuca sativa L.) irrigation water conservation, agro-physiological aspects, and nutritional characteristics. The experiment also involved the use of five different types of soil mulching films: white geotextile (WGup), green geotextile (GGup), black plastic (BPup), white geotextile for both above and below ground (WGup-down), green geotextile for both above and below ground (GGup-down), in addition to un-mulched soil (control). The findings demonstrated that the application of WGup, BPup, WGup&down, and GGup&down resulted in a significant improvement in irrigation water conservation, with WGup exhibiting the highest savings at 41.86%, while the control group exhibited the least amount of water savings at 19.87%. Moreover, the highest productivity levels were observed in plants mulched with GGup&down, reaching 47,944.68 kg ha−1, whereas the lowest productivity was recorded in plants mulched with green geotextile GGup at 22,377.89 kg ha−1. In terms of irrigation water productivity (IWP), the order of effectiveness was BPup > GGup-down > WGup > WGup-down > GGup > Control, with BPup achieving the highest IWP at 60.19 kg m−3 and the control treatment reporting the lowest at 27.80 kg m−3. The percentage of the irrigation water applied for crop evapotranspiration (Irc) showed that the control treatment saved the least amount of irrigation water, saving only 19.87%, while the best treatment was WGup, achieved the highest percentage of irrigation water savings at 41.86%. Additionally, mulched plants exhibited higher levels of nutrients (N, P, Ca, Mg, Fe, Mn, and Zn), ascorbic acid (AsA), and total phenol content (TPC), while showing lower nitrate content in the leaves compared to non-mulched plants. Overall, the utilization of soil moisture-based capacitance sensors and biodegradable mulching films has proven to be highly effective and low cost by 16.633 US$ year−1 to enhance irrigation water productivity, growth performance, nutritional quality, and overall productivity of lettuce crops, thereby contributing to the sustainability of lettuce production in arid regions.

Characteristics of microplastics and their abundance impacts on microbial structure and function in agricultural soils of remote areas in west China

As an emergent pollutant, microplastics (MPs) are becoming prevalent in the soil environment. However, the characteristics of MPs and the response of microbial communities to the abundance of MPs in agricultural soils in West China still need to be elucidated in detail. This study utilized the Agilent 8700 Laser Direct Infrared (LDIR) to analyze the characteristics of small-sized MPs (20–1000 μm) in soils from un-mulched and mulched agricultural fields in West China, and illustrated their correlation with microbial diversity. The results revealed a higher abundance of MPs in mulched soil ((4.12 ± 2.13) × 105 items kg−1) than that in un-mulched soil ((1.04 ± 0.26) × 105 items kg−1). The detected MPs were dominated by fragments, 20–50 μm and Polyamide (PA). High-throughput sequencing analysis indicated that alpha diversity (Chao1 and Shannon indices) in the plastisphere was lower compared to that in soil, and varied significantly with MPs abundance in soil. As the abundance of MPs increased, the proportion of soil about the degradation of organic matte and photoautotrophic taxa increased, which showed enrichment in the plastisphere. Functional predictions further indicated that MPs abundance affected potential soil functions, such as metabolic pathways associated with the C and N cycling. The plastisphere showed higher functional abundance associated with organic matter degradation, indicating higher potential health risks compared to soil environments. Based on the RDA analyses, it was determined that environmental physicochemical properties and MPs abundance had a greater impact on fungal communities than on bacterial communities. In general, the abundance of MPs affected the microbial diversity composition and potentially influenced the overall performance of soil ecosystems. This study offers empirical data on the abundance of MPs in long-term mulched agricultural fields and new insights for exploring the ecological risk issues associated with MPs.

Effect of Mulching on Soil Quality in an Agroforestry System Irrigated with Reused Water

In this study, a special rice-energy willow/poplar agroforestry system was used to analyze the effects of reused water irrigation and mulching on soil salinity, earthworm biomass and abundance, soil organic matter (SOM) content and weed coverage in treerow-dependent habitats. After three-year-irrigation, we investigated the woody line (WL), the buffer zone (BZ) and the crop line habitats (CL). Between 2019 and 2021, we collected data on the distribution of soil-specific electrical conductivity (EC), ammonium-lactate soluble sodium (AL-Na) and exchangeable cations (Na+, K+, Ca2+, Mg2+) and soil NO2− + NO3−-N contents from CL habitats irrigated with effluent water from an intensive catfish farm. Based on our results, significantly greater earthworm abundance (274 pc m−2) and earthworm biomass (54.0 g m−2) values were measured in WL than in BZ or CL habitats. There was no significant difference in weed coverage between the CL (0.61%) and BZ (1.91%), but weeds were significantly denser on the WL (12.3%). In the third year, the EC, AL-Na and ESP values were lower, but the SOM was higher in mulched soil (183.1 mS cm−1, 253.1 mg kg−1, 4.4 ESP% and 4.597%, respectively) than in un-mulched soil.

Mulch film: An overlooked diffuse source of organic ultraviolet absorbers in agricultural soil

Ultraviolet absorbers (UVAs) are emerging pollutants of concern owing to their environmental persistence and endocrine-disrupting effects. UVAs are added to agricultural films to prevent UV-induced degradation, potentially leading to the release of UVAs into the soil. In this study, the occurrence of four frequently used UVAs (UV-324, UV-326, UV-328, and UV-531) in film-mulched agricultural soils (using conventional polyethylene films and biodegradable films) was investigated. Results showed that the UVA concentrations were several orders of magnitude higher in film-mulched soil (mean 91.4 μg/kg) than in unmulched soil (mean 0.08 μg/kg), indicating that mulch films are important sources of UVAs released into agricultural soil. Notably, the mean UVA concentration was up to 10 times higher in biodegradable-film-mulched soils than in polyethylene (PE) film-mulched soils; this result is consistent with our finding that the mean UVA concentration was 448 times higher in commercial biodegradable films than in PE films. In simulated migration experiments, UVAs migrated more readily into the soil from the biodegradable film than from the PE film. To our knowledge, this is the first report demonstrating that the use of mulch films may cause the accumulation of UVAs in agricultural soils as non-point sources. In particular, biodegradable plastic mulches can release more UVAs into soils.

Effect of plastic mulch colour and transplanting stage on baby corn plant performance

In Kenya most of the baby corn crops are produced on un-mulched soil. The country experiences rainfall scarcity and extreme weather conditions which affect the productivity as well as the farmers’ income. Mulching and transplanting can be employed as a way mitigating against the two. Plastic mulch colour determines the characteristic optical properties that influence the levels of light radiation reaching the soil, causing increase or decreases in soil temperature thus affecting the performance of plants differently. Similarly, the colour has a direct effect on the amount and type of rays reflected back onto the plant leaves which influences photosynthesis. The experiment was conducted using two varieties Pan-14 and Thai-gold, four different plastic mulch colours and four different transplanting stages in Meru County in Kenya. This was conducted in two seasons of January to April and June to October 2018. After the scientific data analysis, it has proved that varietal differences influence various plant performances in baby corn. Also the plastic mulch film colour had an effect on plant growth and yield. Similarly, the interaction between the plastic mulch colour and baby corn variety influenced the plants performance. However, transplanting stage had no effect on plant performance.

Modelling Soil Water, Salt and Heat Dynamics under Partially Mulched Conditions with Drip Irrigation, Using HYDRUS-2D

Drip irrigation under mulch is a widely used technique in the arid region of northwest China. The partially mulched soil and the bare strips between mulched areas may complicate the migration of water, salt, and heat in soils, and cause lateral salt accumulation on bare soil surfaces. For investigating hydrothermal dynamics and salt distribution patterns under such circumstances, tank experiments with drip irrigation under plastic film on partially mulched soil were conducted under two intensities of drip irrigation (i.e., low (W1) and high (W2)) with the same total irrigation amount. The spatial distributions of soil water, temperature, and electrical conductivity were monitored accordingly. The two-dimensional (2D) model of soil water, salt, and heat transport under drip irrigation and partially mulched soil conditions was established using HYDRUS-2D, and kinetic adsorption during salt migration was considered. The results of the experiments showed that the uneven distribution of the hydrothermal state led to the accumulation of salt on the un-mulched soil surface. Water migrated from where the dripper was located, and heat accumulated mainly in the mulched soil. HYDRUS-2D matched reasonably well with the observed data, with an R2 higher than 0.54. Under the partially mulched conditions, lower intensity of drip irrigation (W1) show higher desalination efficiency in root zones, with less even lateral salt distribution. Scenario simulations further demonstrated that a larger total irrigation amount would result in a larger desalination zone, and drip irrigations with appropriate incremental intensity could improve salt leaching in the root zone with increased lateral migration of water.

Effects of superhydrophobic sand mulching on evapotranspiration and phenotypic responses in tomato (Solanum lycopersicum) plants under normal and reduced irrigation.

Irrigated agriculture in arid and semi-arid regions is a vital contributor to the global food supply. However, these regions endure massive evaporative losses that are compensated by exploiting limited freshwater resources. To increase water-use efficiency in these giga-scale operations, plastic mulches are utilized; however, their non-biodegradability and eventual land-filling renders them unsustainable. In response, we have developed superhydrophobic sand (SHS) mulching technology that is comprised of sand grains or sandy soils with a nanoscale coating of paraffin wax. Here, we investigate the effects of 1cm-thick SHS mulching on the evapotranspiration and phenotypic responses of tomato (Solanum lycopersicum) plants as a model system under normal and reduced irrigation inside controlled growth chambers. Experimental results reveal that under either irrigation scenario, SHS mulching suppresses evaporation and enhances transpiration by 78% and 17%, respectively relative to the unmulched soil. Comprehensive phenotyping revealed that SHS mulching enhanced root xylem vessel diameter, stomatal aperture, stomatal conductance, and chlorophyll content index by 21%, 25%, 28%, and 23%, respectively, in comparison with the unmulched soil. Consequently, total fruit yields, total dry mass, and harvest index increased in SHS-mulched plants by 33%, 20%, and 16%, respectively compared with the unmulched soil. We also provide mechanistic insights into the effects of SHS mulching on plant physiological processes. These results underscore the potential of SHS for realizing food-water security and greening initiatives in arid regions.

Soil erodibility after the removal of wood chip mulch: A wind tunnel experiment

Numerous field studies have investigated the effects of mulching on soil wind erosion. However, little is known about the changes in soil erodibility after removing the mulch layer. In this paper, we measured the physicochemical properties and aggregate characteristics of soil from an urban park after removing the mulch layer and estimated wind-erodible materials emission by wind tunnel experiments. Wood chips at 4,500 g m⁻² (mulch thickness of 5 cm, R5), 6,300 g m⁻² (mulch thickness of 7 cm, R7), and 8,100 g m⁻² (mulch thickness of 9 cm, R9) were used for mulching an area in Yuanmingyuan Park from October of 2019 to the end of February of 2021. The following four treatments were listed: unmulched soil (CK), R5, R7, and R9. Compared with CK, the soil moisture content (SM), the macro-aggregates (&gt;0.25 mm) ratio (M &gt; 0.25), the wind erodible fraction (WEF), and the dry aggregate stability (DAS) of R5, R7, and R9 were significantly increased after mulching (<i>P</i> &lt; 0.05), whereas the soil organic matter content (SOM) was only slightly increased. The calcium carbonate contents (CaCO₃) varied greatly among the different treatments. Based on the wind tunnel experiments, the distribution of wind erosion materials near the soil surface (0 to 30 cm) was fitted to logarithmic, power, and exponential functions (<i>R</i>² ranged between 0.7179 and 0.9859). The particle size distribution of all wind-erodible materials was unimodal, and the proportion of coarse particles (250 to 100 μm) was highest. Compared with the CK, the average wind erosion rate (AWER) of R5, R7, and R9 was decreased by 48.44%, 65.04%, and 70.03%, respectively, after mulching. The AWER was significantly (<i>P</i> &lt; 0.01) negatively correlated with SM, M &gt; 0.25, WEF, and DAS, and negatively correlated with CaCO₃ and SOM. The CaCO₃ was significantly (<i>P</i> &lt; 0.05) positively correlated with M &gt; 0.25, WEF, and DAS. Overall, despite the relatively short mulching period (16 months), wood chip mulch improved the physicochemical properties and aggregate characteristics of soil and decreased erodibility.

Režim vlažnosti hortisola i prinos salate u uvjetima primjene različitih malčeva

The aim of the study was to determine the impact of dead organic mulches (unprocessed sheep wool - SW and ecological wool - EW), black polyethylene film (PE) and unmulched soil (WM) on the moisture regime of Hortisol and the yield of lettuce cv.´Melina´.The research was carried out at an trial field at the Faculty of Agriculture in Zagreb from April to June 2017. The experiment was set out according to a randomized block design with three replications. Soil samples were taken decadally from depths of 0-10 cm and 10-20 cm, in 3 replications, and the soil moisture content was determined by gravimetric method. The current moisture content in the soil was significantly influenced by: days after transplatation lettuce to open field (DAT) and mulch (M). The significantly low values of soil moisture were determined at 46 DAT, and high at 5 DAT. Considering the mulch, the soil moisture in both layers as follows: PE> SW> EW> WM. Diameter of the lettuce rosette was not significantly affected by the mulch type. Lettuce rosette, grown on SW (20.7 cm) was significantly higher compared to PE (18.4 cm), EW (18.0 cm) and WM (17.8 cm). The highest marketable yield of lettuce was achieved when wool mulch was applied (6.58 kg/m2 on EW, ie 6.56 kg/m2 on SW), and the lowest under PE (4.60 kg/m2). Woolen mulches have proved to be a good alternative to the previous application of PE mulches.

Comparison of plastic film, biodegradable paper and bio-based film mulching for summer tomato production: Soil properties, plant growth, fruit yield and fruit quality

Plastic film (PF) is a common soil mulching material used worldwide in crop production. In recent years there is an increasing demand for reducing the use of PF because of potential environmental- and ecological-risks. Although biodegradable paper (BP) and bio-based film (BB) have been used as alternatives to PF, little information is available regarding their efficiency in summer crop production, which is often restricted by the combination of heat stress and drought stress. To meet this need, PF (silver-gray plastic film made from polyethylene), BP (biodegradable paper made from plant straw) and BB (bio-based film made from plant straw combined with decomposed coal) were used as soil mulching materials to investigate their influence on soil properties (temperature, moisture, pH, electricity conductivity (EC), nutrients and enzymes), plant growth (root morphology, the relative growth rate (RGR), plant biomass and the root/shoot ratio), fruit yield and fruit quality. The un-mulched soil served as control. The trial was conducted in a five-year-old commercial greenhouse located in Helan county, Ningxia, China, with the mean air temperatures of about 32 °C and 31 °C during the summer season in 2016 and 2017, respectively. In general, although PF mulching increased soil moisture, it increased soil temperature, pH and EC and decreased available P, resulting in the reduction of plant growth (root length and diameter, the RGRs of plant height and leaf area, and shoot and root biomass) and fruit yield. The BB mulching decreased soil temperature, however, it decreased soil moisture and invertase and increased soil EC, leading to reduced root growth (root diameter and biomass, and the root/shoot ratio). The BP mulching not only decreased soil temperature, but also increased soil moisture. As a result, it showed several advantages such as decreasing soil EC, increasing soil enzyme activities, improving plant growth (root length, the RGRs of plant height and leaf area, plant biomass and the root/shoot ratio) and increasing fruit yield. Moreover, the fruit quality was partly improved by BP mulching due to reduced nitrate but increased vitamin C. Our results infer that BP was a potential mulching material that could be used for summer tomato production.

A model for the assessment of the effect of mulching on aquifer recharging by rainfalls in an arid region

In this paper, a model is proposed for the assessment of the effectiveness of various mulches in increasing deep percolation of rainfalls for enhancing arid zones aquifers. For this purpose, 8 precipitations were selected from the Intensity-Duration-Frequency (IDF) curves of the study area with a return period of 2 and 5 years. The deep percolation of these precipitations were examined in lysimeters with gravel, sand and mixed mulches and without any mulch. Then 192 data of soil moisture, daily maximum air-temperature and deep percolation were measured for driving empirical equations. Moreover, the efficiency and accuracy of these empirical equations were investigated using Coefficient of Determination (CD) and Nash–Sutcliffe Efficiency Coefficient (NSEC). The results showed that the obtained empirical equations could estimate deep percolation and evaporation with an acceptable accuracy. Using these equations and the soil-water balance equation, a soil moisture model was developed for the assessment of deep percolation. Then it was examined to evaluate the efficiency of the mulched soils in increasing soil moisture and aquifer recharging of three years’ precipitations in Shahrekord plain, Iran. The results showed that the deep percolation increased in all examined mulched soils compared to unmulched soil, its maximum and cumulative increase were in gravel mulch with 21.3% and 30%, respectively. Furthermore, groundwater modeling results showed that the mulching could improve groundwater level as 0.34 m over a three year period. Finally, this paper proposes soil mulching for enhancing groundwater resources and a model to assess it.

Growth and yield of okra (Abelmoschus esculentus (L.) Moench) grown in the marginal upland area of Sta. Rita, Samar as influenced by different planting densities and mulching materials

Okra or Lady’s finger, botanically known as Abelmoschus esculentus (L.) Moench, is a tropical and sub-tropical indigenous vegetable crop commonly grown for its fibrous, slimy, and nutritious fruits and consumed by all classes of population. It has also several medicinal and economic values. Despite its many uses and potential value, its importance is under estimated, under-utilized, and considered a minor crop and little attention was paid to its improvement. The study was conducted to evaluate the effects of different planting densities and mulching materials on the growth and yield of okra grown in slightly sloping area in the marginal uplands in Sta. Rita, Samar, Philippines. A split-plot experiment was set up with planting density as main plot and the different mulching materials as the sub-plot which were: unmulched or bare soil, rice straw, rice hull, hagonoy and plastic mulch. Planting density did not significantly affect the growth and yield of okra. Regardless ofthe mulching materials used, mulched plants were taller and yielded higher compared to unmulched plants. Moreover, the use of plastic mulch resulted to the highest total fruit yield. The results indicate the potential of mulching in increasing yield and thus profitability of okra production under marginal upland conditions.

Effect of mulching on soil environment, microbial floraand growth of potato under field conditions

Mulches modify hydrothermal regime, recycles plant nutrients, promote crop development and increase yields. The impact of straw mulch and different doses of recommended nitrogen was studied on soil microbial flora, soil physico-chemical properties and plant growth parameters of potato at different time intervals under field conditions. Maximum bacterial population (75× 107 cfu g-1 soil), plant growth promoting rhizobacteria count (63× 105 cfu g-1 soil) and fungal population (69× 103 cfu g-1 soil) were observed with the treatment having rice straw mulch @ 6 tonnes/ha and 100% N-level while diazotrophic count (42× 105 cfu g-1 soil) was found with treatment having mulch (6t) but no nitrogen fertilizer at 30 DAS. Mulched soil samples gave statistically higher microbial population. The soil pH and the electrical conductivity of soil were not significantly affected by the different applications. A slight improvement in soil organic content was observed in mulched (0.32%) over unmulched (0.24%) soil samples at 90 DAS. The mineral nitrogen content of soil i.e. ammonical (235.2 kg/ha) and nitrate (156.8 k/ha) nitrogen were greatly affected at 90 DAS by mulching and higher doses of nitrogen fertilization. The altered microbial population helps in improving the various growth parameters of potato plants. Maximum chlorophyll content (1.84 mg/g), maximum dry root-shoot biomass (0.7 g/pl and 5.8 g/pl) and maximum yield (366.8 q/ha) were observed with the treatment having mulch and 100% N-level. It is also concluded that mulch increased the minimum soil temperature by 2-30C and lower down the maximum by 2 to 80C.

Soil Management in the Breede River Valley Wine Grape Region, South Africa. 2. Soil Temperature

Five soil management practices (treatments) were applied in a micro-sprinkler irrigated Chardonnay/99 Richter vineyard on a sandy clay loam soil near Robertson, commencing in April 1993 (one year after planting). The effect of the treatments on the soil temperature at a depth of 200 mm was measured on an hourly basis from April 1995 to March 1999. Differences in soil temperature between the un-mulched and mulched treatments, as measured in the grapevine rows, were negligible from late April to the end of August. From mid-September (grapevine bud break) to the end of March, the temperature of the mulched soil was, with the exception of the third week in October, lower than that of the un-mulched soil. Results indicated that soil temperatures during early spring had a slight effect on the onset of grapevine bud break. Mulching minimised the diurnal variation in soil temperature. The annual cover crop did not cause any delay in bud break and kept the soil temperatures below 25°C, with the exception of a three week period just before harvest.

Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Purple soil is widely distributed in the hilly areas of the Sichuan basin, southwest China, and is highly susceptible to water erosion. The triggering of this process is related to slope, rainfall intensity and surface cover. Therefore, this study assesses the effects of different simulated rainfall intensities with different slopes on hydrological and erosional processes in un-mulched and mulched purple soils. Results show that the sediment and water losses increased with an increase of rainfall intensity and slope steepness. Generally, the slope contribution (Sc) on water and sediment losses decreased with increasing rainfall intensity and slope steepness under both un-mulched and mulched soil. In un-mulched conditions, water losses were independent of slope steepness (Sc &lt; 50%) during the highest rainfall intensity. However, in mulched soil, the higher contributions of slope (Sc) and rainfall (Rc) were found for water and sediment losses, respectively, i.e., &gt;50%, except during the increase in slope steepness from 15° to 25° under the highest rainfall intensity (120 mm·h−1). The effectiveness of mulch was more pronounced in reducing sediment losses (81%–100%) compared with water losses (14%–100%). The conservation effectiveness of mulch both decreased and increased with slope steepness for water and sediment losses, respectively, under higher rainfall intensities. Water infiltration and recharge coefficient (RC) decreased with an increase of slope steepness, while with an increase in rainfall intensity, the water infiltration and RC were increased and decreased, respectively, in both un-mulched and mulched soil. On the other hand, mulched soil maintained a significantly (α = 0.05) higher infiltration capacity and RC compared to that of the un-mulched soil.

Straw mulch can induce greater soil losses from loess slopes than no mulch under extreme rainfall conditions

Mulching a soil has long been considered an effective way of reducing soil and water losses as compared to an un-mulched soil. However, under certain conditions of extreme rainfalls, a soil may be more susceptible to rill erosion under a straw mulch cover, where the mulch can concentrate overland flow, than without such a cover if the soil developed a resistant surface seal. This study used two typical soils of the Loess Plateau of China (a silt loam and a clay loam) to study mulch induced erosion under intense simulated rainstorms of 100, 140 and 180mmh−1 amounting to a rainfall depth of 60mm on 5-m slopes set at different gradients. Under three mulch rates tested (0, 0.2, and 0.8kgm−2), application of mulch always reduced runoff from the soils. No rills were formed in the silt loam soil without a mulch cover under any of the experimental rainfall conditions due to the formation of a seal that resisted rill formation. However, under the 0.8kgm−2 mulch treatment, rills were initiated under all but the least severe experimental conditions combinations and soil losses exceeded those from the soil without mulch. In one case, the soil loss under the mulch was almost three times that from the soil without mulch. In the clay loam soil, which developed a more erodible seal than the silt loam soil, rills were formed under all mulch treatments and rainfall intensity and slope conditions, with the exception of the mulch covered soil under one set of conditions. At the end of the 60-mm rainstorm and under the most intense conditions, the total soil loss from the clay loam soil under mulch (0.8kgm−2) was less than 50% of that from the soil without mulch and in all cases total soil loss was reduced by mulch; however, towards the end of the storm, the soil loss rates, which had been increasing, exceeded those of the un-mulched soil. These phenomena were attributed to the relatively high resistance to rill formation of the surface seal developed on the silt loam soil as compared to the soil without a seal under the high mulch rate, which protected the soil from raindrop impact. Rill initiation was more likely to occur under the mulch due to the increased surface roughness of a soil without a seal and the presence of the mulch, and to individual straws of the mulch laying directly on the soil surface diverting and concentrating soil surface runoff. The results suggest that, with a greater amount of runoff, the same phenomenon may occur on the clay loam soil, which was more susceptible to rill formation under all mulch treatments and developed a less resistant seal. Reducing the mulch rate when severe runoff events are likely from soils similar to the silt loam should avoid such large soil losses. However, for soils more susceptible to rill formation under mulch, such as the clay loam in this study, this may not be effective. Future studies, and especially field studies, should address this issue.

The Influence of Mulching and GA3+Iron Mixture on Head Folding,Bitterness and Quality of Produced Seeds of Lettuce Lactuca sativa var. Longifolia cv. Marul.

This study was carried out during the period between November, 2013 and August, 2014&#x0D; to decrease unfolding, bitterness and tip burns through adopting a new screening method&#x0D; and to produce lettuce seeds and head yields of high qualities. Seeds and plants raised&#x0D; from them were treated with mixtures of [0 and 10 mg.l-1 GA3 + 25 mg.l-1 Fe, 10 mg.l-1&#x0D; GA3 + 50 mg.l-1 Fe and 10 mg.l-1 GA3+ 75mg.l-1 Fe]. Plants grown on mulched and&#x0D; unmulched soils. Mulched soil plants displayed superiority over bare soil in terms:&#x0D; number of unfolded leaves, stem length and leaves number by 48.75, 110.85 and&#x0D; 22.23%, respectively. However, unmulched soil bypassed mulched soil in T.S.S. and dry&#x0D; matter percentages of folded leaves, unfolded leaves, stem and folded leaf base (23.96,&#x0D; 19.41, 30.59, 22.17, 18.52, 28.6, 18.54 and 27.24%, respectively). Lettuce grown on&#x0D; mulched soil revealed superiority over that grown on bare soil in N content of folded and&#x0D; unfolded leaves (23.1 and 68.75%, respectively), K content of folded leaves, stem and&#x0D; folded leaf base (57.85, 42.02 and 24.43%, respectively), Fe content of stem and folded&#x0D; leaf base (106.11 and 54.02 g.kg-1, respectively), Ca content of folded leaves, unfolded&#x0D; leaves, stem and folded leaf base (424.09, 235.96, 206.02 and 296.78%, respectively). 10&#x0D; mg.l-1 GA3 + 75 mg.l-1 Fe displayed preponderance over untreated plants in head fresh&#x0D; weight (26.43%), head yield (26.16%), TSS (15.52%), branches number after chopping&#x0D; (92.9%), branch heights (66.98%) leaf number (30.82%), B content of folded leaves and&#x0D; stem (143.23 and 57.89%, respectively), N content of the folded leaf base (49.73%), K&#x0D; content of folded leaves (7.15%), Fe content of stem (152.14%) and Cu content of stem&#x0D; (39.54%). Lettuce plant treated by 10 mg.l-1 GA3 + 50 mg.l-1 Fe grown on mulched soil&#x0D; overwhelmed other dual interaction treatments as it showed the highest values in head&#x0D; fresh weight (821 g), head yield.m-2 (4.93 kg), weight of folded leaves (483.75 g),&#x0D; number of unfolded leaves (23.75) and weight of unfolded leaves (335 g).

Yield potential and fruit quality of scallop squash (Cucurbita pepo L. var. patissonina Greb. f. radiata Nois.) cultivars grown for processing

Scallop squash fruits may be harvested at different stages of development. Small size fruits, intended both for the fresh market and the food industry, have the highest biological value. This study was conducted to determine the yield potential of scallop squash cultivars (‘Polo F1’, ‘Disco’, ‘Gagat’, ‘Okra’, ‘Sunny Delight F1’) grown on mulched (black polyethylene foil or black agrotextile) or unmulched soil, and harvested when fruits reached a diameter of 3–6 cm. Based on 3-year average data, the highest marketable and early yield was produced by ‘Sunny Delight F1’. This cultivar is also appreciated by consumers for its yellow colored skin of fruits. Another advantage of this cultivar was its high nutritional value expressed by the highest content of dry matter, vitamin C, polyphenols and minerals (K, P, Ca, Mg), with limited tendency to nitrate accumulation. Among the other cultivars tested, ‘Okra’ showed high yield potential, ‘Gagat’ was a rich source of carotenoids, and ‘Disco’ – polyphenols. Black polyethylene foil and black agrotextile appeared to be equally effective mulching materials. The benefit from the application of mulch was a significant increase in yield without any change in the chemical composition of the fruit.

Efficacy of Exotic Control Strategies for Restoring Coastal Prairie Grasses

AbstractRestoration in Mediterranean-climate grasslands is strongly impeded by lack of native propagules and competition with exotic grasses and forbs. We report on a study testing several methods for exotic plant control combined with planting native grasses to restore prairies in former agricultural land in coastal California. Specifically we compared tarping (shading out recently germinated seedlings with black plastic) once, tarping twice, topsoil removal, herbicide (glyphosate), and a control treatment in factorial combinations with or without wood mulch. Into each treatment we planted three native grass species (Elymus glaucus, Hordeum brachyantherum, andStipa pulchra) and monitored plant survival and cover for three growing seasons. Survival of native grass species was high in all treatments, but was slightly lower in unmulched soil removal and control treatments in the first 2 yr. Mulching, tarping, and herbicide were all effective in reducing exotic grass cover and enhancing native grass cover for the first 2 yr, but by the third growing season cover of the plant guilds and bare ground had mostly converged, primarily because of the declining effects of the initial treatments. Mulching and tarping were both considerably more expensive than herbicide treatment. Topsoil removal was less effective in increasing native grass cover likely because soil removal altered the surface hydrology in this system. Our results show that several treatments were effective in enhancing native grass establishment, but that longer term monitoring is needed to evaluate the efficacy of restoration efforts. The most appropriate approach to controlling exotics to restore specific grassland sites will depend not only on the effectiveness, but also on relative costs and site constraints.

Drainage beyond maize root zone in an Alfisol subjected to three land management systems at Minna, Nigeria

The objective of this experiment was to estimate drainage beyond maize rooting depth of 80 cm in relation to tillage and mulch by using Darcy Buckingham’s equation for unsaturated, one-dimensional, vertical flow. Three land management systems were investigated, namely; untilled-mulched, tilled-mulched and tilled-unmulched. The three treatments were replicated three times in a randomized complete block design (RCBD). Individual plots had dimensions of 10 m × 10 m and were planted to maize. The mulch material was rice straw and the application rate was 5 t ha-1. Triplicate tensiometers were installed at 70 and 90 cm depth in the three plots that made up the middle replication for the determination of hydraulic gradient across that depth interval on a daily basis for a 97-day evaluation period. The unsaturated hydraulic conductivity of the same depth interval was determined near the experimental site by the instantaneous profile method. The application of 5 t ha-1 of rice straw mulch increased drainage approximately five times and altered the drainage fraction of rainfall from 4 to 22% compared with unmulched soil. Mulch effect on drainage overshadowed tillage effect. Key words: Drainage, unsaturated hydraulic conductivity, tillage, mulch.