Use of soil solarization to control root rots in gerberas (Gerbera jamesonii)

Summary An investigation was conducted during the summer months of 1986–1987 and 1987–1988 in Western Australia to evaluate the effect of soil solarization on the control of root rot of gerbera an also on the microbial and nutrient status of the soil. Infested soil cores were sampled from a site where root-rot was a severe problem and were removed to a non-infested site where they were subjected to soil solarization or fumigation. Soil solarization resulted in reduced root rot (root disease index 28.6%) in comparison to the untreated control (52.0%) 8 months after planting. Plants in the fumigated plots had 15.8% less disease than those in solarized plots. Solarization increased the total numbers of bacteria and actinomycetes, and the proportion of bacteria and fungi antogonistic to Fusarium oxysporum, F. solani and Rhizoctonia solani. The proportion of actinomycetes antagonistic to these fungi, however, did not differ between solarized and control soil treatments. There was a significant reduction in disease in plants grown in infested fumigated soil to which a 10% concentration of solarized soil had been added, suggesting the development of microbial suppression in solarized soil. Phytophthora cryptogea was eradicated to 30 cm by solarization as well as by fumigation. Solarization eliminated R. solani but not F. oxysporum to a soil depth of 10 cm. Solarization increased the levels of NO _n3 ^– -N and NH₄ ⁺-N in soil, but did not affect the concentrations of PO₄ ^3–, K⁺, Fe²⁺, organic C and pH. Yield (as number of flowers per plant) was increased by soil solarization and by fumigation.Increased yields and decreased disease severity in the solarized plots could have been caused by (1) a reduction in the infectivity of the infested soils, (2) an increase in the suppressiveness of the soil, and (3) an increased available of plant nutrients.     

Evaluation of soil solar heating for control of damping-off fungi in two forest nurseries in France

Field experiments were carried out at two different forest nurseries during the summer of 1994 to examine the efficacy of soil solarization for the control of damping-off. Both soils hosted Pythium spp., Fusarium spp. and Rhizoctonia solani as damping-off agents. Soil samples from solarized, steamed, fumigated and untreated plots were periodically collected and assayed for soil infectivity. Solarization with a double layer of polyethylene film was as effective as steaming or fumigation in reducing soil infectivity in the uppermost layer. During July the temperature of covered beds rose as high as 50°C at a soil depth of 5cm. The method achieved good control of Pythium spp., the main cause of damping-off at both nurseries, whereas Fusarium spp. were more tolerant. The association of Trichoderma spp. with a reduction of soil infectivity at the last sampling date strongly suggested that biocontrol processes were induced after solarization. Soil solarization provides a suitable method for control of damping-off. Received: 29 October 1996     

Fluctuations in the abundance of ammonia oxidizers and the contents of inorganic nitrogen in solarized soil

Solarization makes a great impact on the abundance of ammonia oxidizers and nitrifying activity in soil. To elucidate fluctuations in the abundance of ammonia oxidizers and nitrification in solarized soil, copy numbers of amoA gene of ammonia-oxidizing bacteria (AOB) and archaea (AOA), viable number of ammonia oxidizers and inorganic nitrogen contents were investigated in greenhouse experiments. The copy number of amoA gene and the viable number of ammonia oxidizers were determined by the quantitative polymerase chain reaction and most probable number methods, respectively. Abundance of AOB based on the estimation of amoA gene copy numbers and viable counts of ammonia oxidizers was decreased by the solarization treatment and increased during the tomato (Solanum lycopersicum L.) cultivation period following the solarization. Effect of solarization on the copy number of amoA gene of AOA was less evident than that on AOB. The proportion of nitrate in inorganic nitrogen contents was declined by the solarization and increased during the tomato cultivation period following the solarization. Positive correlations were found between the proportion of nitrate in inorganic nitrogen content and the copy number of bacterial or archaeal amoA gene or the viable number of ammonia oxidizers; the copy number of bacterial amoA gene showed a strong correlation with the viable number of ammonia oxidizers. The present study revealed influences of solarization on the fluctuation in the abundance of ammonia oxidizers and dynamics of inorganic nitrogen contents in soil and the results indicate that the determination of amoA gene of AOB is possibly a quick and useful diagnostic technique for evaluating suppression and restoration of nitrification following solarization.     

Impact of soil solarization on the ciliate community structure of a greenhouse soil

Soil solarization is an ecologically friendly method of controlling various plant pathogens and pests, but also affects non-pathogenic members of the soil biota. Here, we studied the impact of soil solarization on the community structure of soil ciliates using a culture-independent molecular approach, namely denaturing gradient gel electrophoresis (DGGE) of targeted 18S rRNA gene fragments. Greenhouse soil with added organic fertilizers was solarized for 33 days at an average temperature of 47–48°C. Solarization caused a drastic change in the ciliate community. The variation between replicates was large, which suggested that the distribution of ciliates was spatially heterogeneous in the soil, probably due to their decreased numbers. In contrast, non-solarized soil had a stable and homogeneous ciliate community during the experimental period. In solarized soil, most of the original ciliate community recovered 76 days after solarization. Sequence analysis of DGGE fragments indicated that both r-selected and K-selected species of ciliates were affected by solarization but recovered with time after solarization. Our results demonstrated both the vulnerability and resilience of the ciliate community to soil solarization and also the utility of using molecular-based analysis of ciliate communities as bioindicators of soil stress caused by solarization.     

Inactivation of Escherichia coli in soil by solarization

Abstract

Contamination of agricultural soil by fecal pathogenic bacteria poses a potential risk of infection to humans. For the biosafety control of field soil, soil solarization in an upland field was examined to determine the efficiency of solarization on the inactivation of Escherichia coli inoculated into soil as a model microorganism for human pathogenic bacteria. Soil solarization, carried out by sprinkling water and covering the soil surface with thin plastic sheets, greatly increased the soil temperature. The daily average temperature of the solarized soil was 4–10°C higher than that of the non-solarized soil and fluctuated between 31 and 38°C. The daily highest temperature reached more than 40°C for 8 days in total in the solarized soil during the second and third weeks of the experiment. Escherichia coli in the solarized soil became undetectable (< 0.08 c.f.u. g^?1 dry soil) within 4 weeks as a result, whereas E. coli survived for more than 6 weeks in the non-solarized soil. Soil solarization, however, had little influence on the total direct count and total viable count of bacteria in the soil. These results indicate that soil solarization would be useful for the biosafety control of soil contaminated by human pathogens via immature compost or animal feces.     

Soil Solarization: Effects on Soil Microbiological Parameters

Soil solarization, obtained by covering soil with plastic films, is a useful practice able to reduce soil pathogen populations. Light plastic films (LPFs) are nowadays widely used especially in open and greenhouse vegetable crop cultivations in Southern Italy, as they are able to raise soil temperature more than 20°C above air temperature. The solarization treatment with LPFs is characterized by a low cost and low environmental impact.

The wide use of these technique causes a concern about the side effect of solarization on soil microbial populations, which are affected the same as plant pathogens by soil heating. As scientific literature pays scant attention to the effect of soil heating on soil microbial parameters, this paper studied the effects of solarization on soil microbial biomass, soil respiration, and soil enzymatic activity in the presence of organic amendments and the soil fumigant dazomet.

Solarization appears to be an effective practice able to control nematodes, even though it may cause serious stress on the soil microbial biomass. In addition, it was demonstrated that the organic amendments exert a protective role keeping soil microbial biomass and enzymatic activities protected from the detrimental effect of heating.     

Inactivation of Escherichia coli in soil by solarization

Contamination of agricultural soil by fecal pathogenic bacteria poses a potential risk of infection to humans. For the biosafety control of field soil, soil solarization in an upland field was examined to determine the efficiency of solarization on the inactivation of Escherichia coli inoculated into soil as a model microorganism for human pathogenic bacteria. Soil solarization, carried out by sprinkling water and covering the soil surface with thin plastic sheets, greatly increased the soil temperature. The daily average temperature of the solarized soil was 4–10°C higher than that of the non-solarized soil and fluctuated between 31 and 38°C. The daily highest temperature reached more than 40°C for 8 days in total in the solarized soil during the second and third weeks of the experiment. Escherichia coli in the solarized soil became undetectable (< 0.08 c.f.u. g⁻¹ dry soil) within 4 weeks as a result, whereas E. coli survived for more than 6 weeks in the non-solarized soil. Soil solarization, however, had little influence on the total direct count and total viable count of bacteria in the soil. These results indicate that soil solarization would be useful for the biosafety control of soil contaminated by human pathogens via immature compost or animal feces.     

Soil solarization: Effects on soil properties,crop fertilization and plant growth

Summer solarization of six wet field soils of four different textures raised soil temperatures by 10–12°C at 15cm depth. Soil solarization increased concentrations of NO^?₃N and NH⁺₄N up to six times those in nontreated soils. Concentrations of P, Ca²⁺, Mg²⁺ and electrical conductivity (EC) increased in some of the solarized soils. Solarization did not consistently affect available K⁺, Fe³⁺, Mn²⁺, Zn²⁺, Cu²⁺, Cl^? concentrations, soil pH or total organic matter. Concentrations of mineral nutrients in wet soil covered by transparent polyethylene film, but insulated against solar heating, were the same as those in nontreated soil. Increases in NO^?₃N plus NH⁺₄N were no longer detected in fallowed soils 9 months after solarization. No significant correlation between mineral-nutrient concentration in plant tissue and plant growth was found. Fresh and dry weights of radish, pepper and Chinese cabbage plants usually were greater when grown in solarized soils than in nontreated soils. Fertilization of solarized soils sometimes resulted in greater plant growth responses than observed in solarized but nonfertilized soils.     

Displacement of native rhizobia nodulating chickpea (Cicer arietinum L.) by an inoculant strain through soil solarization

Summary Soil solarization greatly reduced the native chickpea Rhizobium population. With inoculation, it was possible to increase the population of the Rhizobium in solarized plots. In the 1st year, 47% nodulation was obtained with chickpea inoculant strain IC 59 when introduced with a cereal crop 2 weeks after the soil solarization and having a native Rhizobium count of <10 g^-1 soil, and only 13% when introduced 16 weeks after solarization at the time the chickpeas were sown, with 2.0×10² native rhizobia g^-1 soil. In the non-solarized plots inoculated with 5.6×10³ native rhizobia g^-1 soil, only 6% nodulation was obtained with the inoculant. In the succeeding year, non-inoculated chickpea was grown on the same plots without any solarization or Rhizobium inoculation. The treatment that showed good establishment of the inoculant strain in year 1 formed 68% inoculant nodules. Other treatments indicated a further reduction in inoculant success, from 1%–13% to 1%–9%. Soil solarization thus allowed an inoculant strain to successfully displace the high native population in the field and can serve as a research tool to compare strains in the field, irrespective of competitive ability. In year 1, Rhizobium inoculation of chickpea gave increased nodulation and increased plant growth 20 and 51 days after sowing, and increased dry matter, grain yield, and grain protein yield at maturity. These beneficial effects of inoculation on plant growth and yield were not measured in the 2nd year.Submitted as Journal Article No. JA 945 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India     

Soil solarization enhances growth and yield in dry beans

Abstract

Dry beans are one of the most important crops in Mexico. However, in the last decade this crop averaged yields as low as 0.7 tons per hectare. Therefore, the purpose of this study was to test if soil solarization is a suitable pre-planting soil treatment to improve growth, nutrition and yield of beans in northeast Mexico. Five different periods of soil solarization were evaluated during the spring of 2008: 0, 30, 40, 50 and 60 days of soil solarization. Soil temperatures were recorded during soil solarization to estimate total heat units. After soil solarization bean seeds were sown in plastic-mulched rows and leaf area, potassium, calcium and magnesium concentration and yield were measured. Leaf area and concentrations of potassium, calcium and magnesium were increased by all treatments of soil solarization when compared with the non-solarized soil. Sixty days of soil solarization produced yields of 3.7 tons per hectare while no solarization produced yields of 2.1 tons per hectare. Soil heat units were positively correlated with yield, suggesting that the increase in yield is due to an increase in heat accumulation during soil solarization in addition to an increase of leaf area and to an enhancement of plant nutrition.     

The Effects of Soil Solarization and Compost on Soil Suppressiveness against Fusarium Oxysporum f. sp. Melonis

Soil suppressiveness against Fusarium was tested using solarized and non-solarized soils combined with composts of three maturation levels, and a non-amended control. The soils were sampled on three dates: after previous year solarization but before current year solarization (0 weeks), at the end of the solarization period of the current year (4 weeks), and 4 weeks later (recovery time). Melon seedlings were inoculated with Fusarium spores and disease severity was assessed. The study showed a reduction of soil suppressiveness capacity against Fusarium oxysporum f. sp. melonis after 1 year of solarization (0 weeks). Fusarium disease severity in artificially inoculated melon plants, expressed by area under the disease progress curve, was higher in solarized soil than in non-solarized soil. Compost addition lowered the disease severity, both in the solarized and in the non-solarized soils. However, suppression was not obtained at the end of the solarization period, whereas compost beneficial effect was found at this time.     

Improving Soybean Performance in the Northern Great Plains through the Use of Cover Crops

Cover crops are capable of providing multiple benefits for improving soil quality and enhancing annual crop growth. Maintaining continuous plant cover on agricultural fields with cover crop is of great interest to improve nutrient cycling, prevent soil degradation, and promote further adoption of no-till farming systems. A field study was conducted in eastern South Dakota, USA, in 2007, 2008, and 2009 to evaluate four cover crop combinations [(1) no cover; (2) buckwheat (BUCK) (Fagopyrum esculentum Moench) + slender wheatgrass (Agropyron caninum L.) (SLD WHT); (3) oilseed radish (Raphanus sativus L.) (RAD) + SLD WHT; and (4) purple top turnips (Brassica rapa L.) (TURN + SLD WHT)] sown after oat (Avena sativa L.) on soybean [Glycine max (L.) Merr.] performance. The impacts of no tillage (NT) and conventional tillage (CT) were evaluated at two different planting populations. Soybean plant biomass, seed harvest index, yield, total nitrogen (N), oil concentration, and test weight were measured. Cover crops preceding soybean did not negatively impact most measured plant parameters. Seed yield was increased by the RAD + SLD WHT and TURN + SLD WHT in 2008, whereas in 2007 and 2009 no yield increase or slight yield decrease was shown by the cover crops. Soil tillage practice and planting population had a strong influence on seed yield and seed quality in all three study years.     

The influence of phosphate fertilizer application levels and cultivars on cadmium uptake by Komatsuna (Brassica rapa L. var. perviridis)

Cadmium (Cd) is a common impurity in phosphate fertilizers and application of phosphate fertilizer may contribute to soil Cd accumulation. Changes in Cd burdens to agricultural soils and the potential for plant Cd accumulation resulting from fertilizer input were investigated in this study. A field experiment was conducted on Haplaquept to investigate the influence of calcium superphosphate on extractable and total soil Cd and on growth and Cd uptake of different Komatsuna (Brassica rapa L. var. perviridis) cultivars. Four cultivars of Komatsuna were grown on the soil and harvested after 60 days. The superphosphate application increased total soil Cd from 2.51 to 2.75?mg?kg^?1, 0.1?mol?L^?1 hydrochloric acid (HCl) extractable Cd from 1.48 to 1.55?mg?kg^?1, 0.01?mol?L^?1 HCl extractable Cd from 0.043 to 0.046?mg?kg^?1 and water extractable Cd from 0.0057 to 0.0077?mg?kg^?1. Cd input reached 5.68?g?ha^–1 at a rate of 240?kg?ha^–1 superphosphate fertilizer application. Superphosphate affected dry-matter yield of leaves to different degrees in each cultivar. ‘Nakamachi’ produced the highest yield in 2008 and ‘Hamami No. 2’ in 2009. Compared with the control (no phosphate fertilizer), application of superphosphate at a rate of 240?kg?ha^–1 increased the Cd concentration in dry leaves by 0.14?mg?kg^?1 in ‘Maruha’, 1.03?mg?kg^?1 in ‘Nakamachi’, 0.63?mg?kg^?1 in ‘SC8-007’ in 2008, and by 0.19?mg?kg^?1 in Maruha’, 0.17?mg?kg^?1 in ‘Hamami No. 2’, while it decreased by 0.27?mg?kg^?1 in ‘Nakamachi’ in 2009. Field experiments in two years demonstrated that applications of different levels of calcium superphosphate did not influence Cd concentration in soil and Komatsuna significantly. However, there was a significant difference in Cd concentration of fresh and dry Komatsuna leaves among four cultivars in 2008 and 2009. The highest Cd concentration was found in the ‘Nakamachi’ cultivar (2.14?mg?kg^?1 in 2008 and 1.91?mg?kg^?1 in 2009). The lowest Cd concentration was observed in the ‘Maruha’ cultivar (1.51?mg?kg^?1?dry weight (DW)) in 2008 and in the ‘Hamami No. 2’ cultivar (1.56?mg?kg^?1?DW) in 2009. A decreasing trend in Cd concentration was found in ‘Nakamachi’, followed by ‘SC8-007’, ‘Hamami No. 2’ and ‘Maruha’ successively. It is necessary to consider a low-uptake cultivar for growing in a Cd polluted soil. In these two years’ results, ‘Maruha’ cultivar was the lowest Cd uptake cultivar compared to the others.     

Fine-Root Production and Aboveground Development for Loblolly Pine,Silver Maple,and Cottonwood

Fine-root production was studied in recently established loblolly pine (Pinus taeda), silver maple (Acer saccharinum), and cottonwood (Populus deltoides) biomass plantations. Dry weights of fine roots produced in ingrowth cores were recorded from April 2008 to March 2009 to quantify the temporal variation of fine-root production among the species. Similarly, fine-root production was compared to the monthly height and diameter increments, soil temperature, and moisture content. Species showed no significant difference in fine-root production; however, fine-root production varied by month. Fine-root production in September was significantly different from that of December and January combined, February, and May. Loblolly pine produced 49 g m^?2, whereas silver maple and cottonwood produced 37 g m^?2 and 35 g m^?2 of fine roots, respectively, during the study period. Fine-root production was not correlated with height increment, diameter increment, soil temperature, and soil moisture.     

Residual effects of soil Zn fertilization on soil characteristics,yield and quality of Platycodon grandiflorum

ABSTRACT

Zinc (Zn) deficiency is common worldwide and is a major limiting factor in the cultivation of Platycodon grandiflorum because most P. grandiflorum is cultivated on soils with slight or severe levels of Zn deficiency in China. To investigate the effects of soil Zn fertilization on P. grandiflorum and its residual effects on soil characteristics, a randomized complete block design was conducted at the experimental station of Shandong Agricultural University China in 2016–2018. In 2016, ZnSO₄ · 7H₂O was used as Zn fertilizer. The fertilizer levels of Zn fertilizer were designed as 0, 4, 6, 8 and 10 kg ha^?1 and were denoted as CK, Zn₄, Zn₆, Zn₈ and Zn₁₀. No Zn fertilizer was used in 2017 and 2018. The results showed that soil Zn fertilization increased the quantity of soil bacteria, and actinobacteria, Zn₈ and Zn₁₀ treatments increased the soil fungal quantity in 2017, whereas the effect was observed only in the Z₁₀ treatment in 2018. Soil Zn fertilization enhanced the activity of polyphenol oxidase, decreased that of phosphatase, and did not influence the invertase activity in both 2017 and 2018. Both the yield and the quality of P. grandiflorum in the succeeding three years increased due to the soil Zn fertilization in 2016. Overall, soil Zn application is a suitable approach to the cultivation of P. grandiflorum, and the residual effects of a one-time soil Zn fertilization could last at least two years.     

Microbial community response to soil solarization in Nepal's rice-wheat cropping system

The Indo-Gangetic Plains of South Asia support 13.5 million hectares of rice-wheat cropping systems, which currently feed over one billion people. Intensified agriculture has resulted in a more than two-fold increase in rice and wheat yields since the 1970s; however, this continuous cropping has also exacerbated weed, pest and disease problems. Soil solarization is an accessible, low-risk management practice for small-holder farmers that has ameliorated these problems in some settings and has the potential to dramatically improve yields. Field trials were conducted at two sites in Nepal to test whether soil solarization: (i) had a lasting effect on soil bacterial, fungal and nematode communities; (ii) altered the rhizosphere communities of rice nursery seedlings and (iii) improved crop growth and yield in the rice-wheat cropping system. Rice seedlings were grown in nursery plots that were solarized for 28 days or left untreated and were transplanted to field plots that were also either solarized for 28 days or not in a randomized complete block design with four replications. Rice was grown to maturity and harvested, followed by a complete wheat cropping cycle. Solarization of main field plots increased counts of fungal propagules and decreased root galling and nematode counts and decreased weed biomass. Terminal restriction fragment length polymorphism (T-RFLP) analyses of extracted soil DNA revealed significant shifts in fungal community composition following soil solarization, which was sustained throughout the entire rice cropping cycle at both field sites. The bacterial community composition was similarly affected, but at only one of the two sites. Despite the observed changes in soil microbial community composition over more than one cropping period, solarization had no impact on crop productivity at either site. Nevertheless, such changes in soil microbial communities in response to solarization may be responsible for increased yields observed at other sites with greater pathogen pressure. This practice has shown promising results in many farmers’ fields in South Asia, but further elucidation of the mechanisms by which solarization increases productivity is needed.     

不同种植年限山银花根区土壤生物特性

[目的]探索喀斯特山区不同种植年限对山银花产地土壤生物学特性的影响,为促进贵州省山银花的高产优质栽培提供基础数据。[方法]采用野外采集和室内分析的方法,以贵州省绥阳县不同种植年限山银花根区土壤为研究对象,对比研究了不同年限土壤生物特征。[结果]随着种植年限的增加,山银花土壤微生物总数和细菌数量(B)在数值上表现为先增加后减少的趋势,放线菌数量(S)和真菌数量(F)呈不断增加的变化趋势;土壤微生物生物量碳、生物量氮和微生物量磷都表现为先增加,后持续减少的趋势;土壤过氧化氢酶和脲酶的活性均有先增加后减少的趋势,土壤磷酸酶有先减少后缓慢增加的趋势;土壤细菌和真菌数比值(B/F)呈先增加后减少趋势,放线菌数量(S)和真菌数量比(S/F)随着种植年限的增加而增加;土壤微生物的Shannon—Wiener指数随着种植年限先增大后减小,Simpson指数和Shannon均匀度指数均随着种植年限呈减少趋势。[结论]随着种植年限的增加,土壤肥力下降,根区病毒害发病率增大。     

Permanent raised beds improved soil structure and yield of spring wheat in arid north‐western China

In arid north‐western China, soil degradation, limited water and subsequent yield decline, largely as a result of excessive tillage and residue removal practices, are the main factors limiting further development of local agriculture. The effects of permanent raised beds (PRB), no‐till (NT) and traditional tillage (TT) on soil structure and yield were investigated in a wheat (Triticum aestivum L.) – maize (Zea mays L.) cropping system from 2004 to 2009 in the Hexi Corridor of Gansu Province, China. PRB and NT had more macro‐aggregates (>0.25 mm, +2.7%), a better distribution of pore size classes and improved hydraulic conductivity, whereas TT soils were dominated by micro‐aggregates and micro‐porosity. In PRB, soil bulk density decreased significantly by 6.3 and 7.0% for the 0‐ to 10‐cm and 20‐ to 30‐cm depths relative to TT. The PRB mean crop yields increased by 4.2% and water use efficiency improved by 21.3% compared with TT because of greater soil moisture and improved soil physical and chemical status. These improvements in soil properties, yield and water use are of considerable importance for soil regeneration, food security and sustainable agriculture in arid regions, such as north‐western China.     

EFFECT OF COTTONSEED MEAL WITH OR WITHOUT SOAPSTOCK,CANOLA MEAL,OR UREA ON SOIL FERTILITY AND GROWTH OF MARIGOLD AND REDBUD

The effects of incorporating or topdressing with cottonseed (Gossypium hirsutum L.) meal with or without soapstock, canola (Brassica rapa L.) meal, urea, or no amendment (control) were investigated using plants of marigold (Tagetes erecta L. ‘Inca II Gold’ or ‘Inca II Yellow’) and redbud (Cercis canadensis L.) in a Norge loam (fine-silty, mixed, thermic Udic Paleustolls) at Stillwater, OK in 2008 and 2009. Fertilizers were applied in May at 4.9 g?m^?2 N based on soil test results prior to the study and nitrogen (N) recommendations for turfgrass. Soil nitrate-nitrogen (NO₃-N) and phosphorus (P) increased from 2008 to 2009 in marigold plots into which cottonseed meal with soapstock was incorporated, and boron (B) increased in all marigold plots regardless of treatment. In 2009, marigolds grown in plots into which cottonseed meal was incorporated were taller than plants in other treatments except the untreated control. Marigolds in plots in which cottonseed meal was topdressed, cottonseed meal with soapstock was incorporated, or urea was topdressed grew less in height than plants in plots with cottonseed meal incorporated or control plots. Shoot dry weights of marigold plants in plots topdressed with cottonseed meal with or without soapstock, urea, or control plots were lower than those of plants in other treatments. Visual ratings of marigold plants receiving a topdress of urea or no treatment were lower than visual ratings of plants in any other treatment in July, but similar in August to those of marigold plants in plots in which cottonseed meal was topdressed. Some differences within fertilizer treatments occurred between 2008 and 2009 in redbud soil concentration of NO₃-N, calcium (Ca), magnesium (Mg), sulfate-sulfur (SO₄-S), iron (Fe), B, and copper (Cu). Leaf P concentration differed among fertilizer treatments in 2009. Leaf and total dry weight of redbuds grown in soil incorporated with urea was greater than that of plants in any other treatment. Results indicate that cottonseed and canola meals provide N and other nutrients for growth of landscape plants. Soil incorporated cottonseed meal encouraged more growth of marigold than soil incorporated urea but less growth of redbud.     

Film fully-mulched ridge-furrow cropping affects soil biochemical properties and maize nutrient uptake in a rainfed semi-arid environment

Abstract

This study evaluated the effects of plastic mulched ridge-furrow cropping on soil biochemical properties and maize (Zea mays L.) nutrient uptake in a semi-arid environment. Three treatments were evaluated from 2008 to 2010: no mulch (narrow ridges with crop seeded next to ridges), half mulch (as per no mulch, except narrow ridges were mulched), and full mulch (alternate narrow and wide ridges, all mulched with maize seeded in furrows). Compared to the no mulch treatment, full mulch increased maize grain yield by 50% in 2008 and 25% in 2010, but reduced yield by 21% in 2009 after low precipitation in early growth. Half mulch had a similar grain yield to no mulch in the three cropping years, suggesting half mulch is not an effective pattern for maize cropping in the area. Mulch treatments increased aboveground nitrogen (N) uptake by 21?34% and phosphorus (P) uptake by 21?42% in 2008, and by 16?32% and 14?29%, respectively, in 2010; but in 2009 mulching did not affect N uptake and decreased P uptake. Soil microbial biomass and activities of urease, β-glucosidase and phosphatase at the 0?15 cm depth were generally higher during vegetative growth but lower during reproductive growth under mulch treatments than no mulch. Mulching treatments increased carbon (C) loss of buried maize residues (marginally by 5?9%), and decreased light soil organic C (15?27%) and carbohydrate C (12?23%) concentrations and mineralizable C and N (8?36%) at harvest in the 0?20 cm depth compared with no mulch, indicating that mulching promotes mineralization and nutrient release in soil during cropping seasons. As a result of these biological changes, mineral N concentration under mulch was markedly increased after sowing in upper soil layers compared with no mulch. Therefore, our results suggest that mulched cropping stimulated soil microbial activity and N availability, and thus contributed to increasing maize grain yield and nutrient uptake compared with no mulch.