Effect of iron deficiency on the growth,development and grain yield of some selected upland rice genotypes in the rainforest

Abstract

Iron deficiency is a major production constraint of upland rice in the tropics despite is abundance in the soil. This investigation aimed to explicate the effect of iron deficiency on the growth, development, grain yield and its attributes of some selected upland rice in the rainforest. Field experiments were established at Africa Rice sub-Station, Ibadan, Nigeria. The treatments consisted of 35 upland rice genotypes and availability of iron in the soil (Fe-sufficient and Fe-deficient). The treatments were arranged in alpha lattice design with three replications. It was observed that upland rice sown in iron (Fe) deficient soils had significantly lower growth (plant height, number of tillers and seedling vigor), flowered later, with significantly lower yield attributes (1000 grain weight, filled grain) and grain yield than those sown in Fe-sufficient soils. Conversely, the number of unfilled grains were significantly higher in upland rice sown in Fe-deficient than those in sufficient soils. Percentage yield loss was in the range 98.00% to 22.95% for China best and Faro 65 respectively. Genotypes were identified to be tolerant (Faro 65, NERICA 3 and IRAT 109) and susceptible (Ofada 2, NERICA 5 and China Best) to Fe-deficiency based on their percentage grain yield loss. These evidences suggested that despite the increased phenology of upland rice sown in Fe-deficient soils their reproductive growth was suppressed through increased number of unfilled grains as witnessed in China Best and Faro 64.     

不同覆盖方式对新复垦区土壤水热及春玉米产量的影响

随着城市化进程的加速发展,我国净耕地面积持续减少,合理开发利用潜在土地资源,对于保障我国粮食安全具有重要意义。为了探讨不同覆盖耕作方式对新复垦区土壤水热及作物生长的影响,通过2018年和2019年连续两年田间试验,研究了传统耕作(CK)、地膜覆盖(FM)、秸秆深埋(BS)和秸秆深埋+地膜覆盖(F+S) 4种处理对土壤水分、温度和春玉米生长及产量的影响。结果表明:2018年,F+S、BS、FM处理玉米生育期内0～20cm及20～40 cm土层平均土壤含水率分别较CK增加24.4%、16.5%、12.6%及9.1%、3.2%、3.7%。2018年玉米苗期, 0～100 cm土壤蓄水量表现为FMF+SCKBS,明显表现为有覆膜处理(F+S和FM)的土壤蓄水量高于不覆膜处理(BS和CK)。2019年玉米苗期,土壤蓄水量则表现为F+SBSFMCK。与CK相比,春玉米全生育期不同覆盖耕作处理条件下各土层(5～25 cm)土壤温度均有所提高,具体表现为F+SFMBSCK,各处理土壤温度随土层深度表现为降低趋势。以表层5 cm土壤温度增幅最大,覆盖耕作处理的增温效应在全生育期表现为前期明显而后期弱化。各处理株高变化趋势一致,在播种后70d左右达到峰值,随后出现小幅度下降并最终保持稳定。试验期,株高和叶面积均表现为地表有覆膜的处理高于未覆膜处理(P0.05)。2018年, F+S、BS和FM处理玉米产量均显著高于CK(P0.05),2018年和2019年,各处理产量分别较CK增加17.0%、13.5%、6.6%和30.5%、23.9%、3.8%。产量构成逐步回归分析结果表明,穗长对产量的影响最大,产量与穗行数和百粒重呈正相关关系。秸秆深埋+地膜覆盖处理(F+S)可以综合发挥二者优势,有效调节土壤水热状况,改善土壤环境,促进作物生长发育,从而获得较高的产量,可作为新复垦区春玉米适宜的种植管理方式。     

Factors associated with annual ryegrass yield response to limestone

Abstract

Quantifying the effects of soil acidity on plant growth remains a challenging research topic as numerous soil and plant growth factors are influenced by pH and lime. In the field, annual ryegrass (Lolium multiflorum Lam. ‘Marshall') responded positively to the application of 3.8 Mg lime/ha on a strongly acid (pH 4.7) Lilbert loamy fine sand (loamy, siliceous, thermic, arenic Plinthic Paleudult) over three growing seasons. Dry matter yield in some cuttings, however, was better correlated with soil Al, P, Ca, Mg, and K than with pH. A greenhouse study was undertaken to quantitatively determine the effects of these five minerals plus Mo on ryegrass yield in limed and unlimed Lilbert soil material. Three ryegrass cuttings were obtained from unlimed (pH 4.8) or limed (1000 mg CaCO₃/kg) Lilbert soil which was also amended with five rates of Ca, K, Mg, Al, P, and Mo in combinations stipulated by central composite design methodology. Response surface models that fit yield to the applied treatments and soil test data were complex because all factors and many interactions were significant. Furthermore, the models were transformed as the plants matured and element availability changed due to mineral uptake. Most yield improvement derived from liming occurred as a result of the elimination of exchangeable Al with a concomitant increase in P efficiency. Applied Ca did not alleviate Al toxicity in unlimed soil. Chlorotic plants developed in all pots where Mg was excluded. Yield was increased by applied Mg and Mo in unlimed soil, but not in limed soil. Applied K improved yield only in limed soil. Although regression accounted for a large portion of the yield variability (R² values ranged from 0.75 to 0.95), these models were unable to accurately predict yield in control treatments.     

Effects of different levels of soil salinity on yield attributes,accumulation of nitrogen,and micronutrients in Brassica spp.

The present study was conducted to assess the effect of soil salinity on yield attributes as well as nutrient accumulation in different plant parts of seven Brassica cultivars from two different species raised in pot culture experiment with two levels of salinity treatments along with control corresponding to soil electrical conductivity (EC) values of 1.65 (S₀), 4.50 (S₁) and 6.76 (S₂) dS m^?1. The experiment was consisted of twelve replications in a completely randomized design. Imposition of salinity stress affected various yield attributing characters including plant height, which ultimately led to severe yield reduction. However, tolerant cultivars, CS 52 and CS 54 performed better under salt treatment showing lesser yield loss. Salinity stress reduced the nitrogen (N) content in leaves of the Brassica plants, which reflected in decreased seed protein content. Reduced accumulation of iron (Fe), manganese (Mn) and zinc (Zn) was observed in leaf, stem and root at flowering and post-flowering stages, while CS 52 and CS 54 showed less reduction than susceptible cultivars under salinity stress.     

Optimizing fertilizers doses and their effects on photosynthesis and biomass yield of Hibiscus cannabinus cultivated on BRIS soil

In tropical climate, huge amount of fertilizer need to be used for the cultivation of kenaf (Hibiscus cannabinus L.) in Beach Ridges Interspersed with Swales (BRIS) soil, however this approach is not cost effective and environmental friendly. Therefore, the optimizing of fertilizer rate for BRIS soils and selection of suitable soil amendments are crucial to get a higher yield. In this study, the effects of different combinations of urea, chicken manure and biochar on soil properties, growth performance and physiological characteristics of kenaf cultivated on the BRIS soil were investigated. Eight treatments were conducted namely: control (T1), biochar (T2), chicken manure (T3), urea (T4), chicken manure + urea (T5), biochar + chicken manure (T6), urea + biochar (T7) and biochar + chicken manure + urea (T8). The biomass and physiological characteristics of kenaf were recorded every month, while the soil was analyzed following a standard laboratory procedure. The application of organic and inorganic fertilizer (urea) significantly increased the nutrient content of the soil compared to the T1, whereas T3 showed the highest pH, cation exchange capacity, and exchangeable bases (Na, Mg, Ca). However, the mixing of biochar with organic and inorganic fertilizers showed the highest plant height, diameter of stem and number of leaves as well as dry biomass compared to other treatments. Furthermore, the application of nitrogen fertilizer significantly increased the photosynthesis rate and stomatal conductivity. The results suggest that the mixing of biochar with organic and inorganic fertilizers represents an effective approach for the cultivation of kenaf in tropical climate.     

Exploring optimal soil mulching to enhance maize yield and water use efficiency in dryland areas in China

Water and nutrient availability significantly limits global crop production, especially for dryland agriculture in arid and semi-arid regions. To explore the optimal soil mulching options for the Loess Plateau in China, a 3-year field study was conducted to investigate the effects of various soil mulching practices on soil temperature and the water use and grain yield of spring maize. The treatments included traditional flat farming (CK), narrow plastic film mulch (NM), wide plastic film mulch (WM) and narrow plastic film mulch?+?maize straw mulch between rows (MS). The results showed that MS treatment increased consistently soil temperature during the initial stages of maize growth, and more importantly, it reduced diurnal temperature variation. MS also increased in soil water storage by 10.1%, leading to the highest water use efficiency (WUE?=?30.9?kg?ha^?1?mm^?1) over CK on 3 year average. MS significantly increased maize yield and net income of farmers by up to 20%, compared to CK. In conclusion, optimisation of soil mulching strategies significantly enhanced crop yield and water productivity in dryland agriculture in China. Our study provides important guidance for exploring better soil management practice for dryland agriculture in the other regions of the world.     

Combination of agricultural waste compost and biofertilizer improves yield and enhances the sustainability of a pepper field

Application of plant growth‐promoting rhizobacteria (PGPR) has been considered as an environmentally friendly method for crop yield promotion as well as plant disease management. Efforts have been devoted to unraveling mechanisms involved in bacteria–plant and bacteria–pathogen interactions. However, little is known on the effect of the interaction among PGPR, soil, and plant. We compared growth and yield promotion capacity of biofertilizer Ning Shield, a consortium of bacterial preparation used as a biofertilizer (BF), and its mixture with compost of agricultural waste including spent substrate of Pleurotus ostreatus (SSP)/Volvariella volvacea (SSV), chicken manure (CM), and inorganic fertilizer (IOF) in a pepper field, respectively. The disease control efficacy, pepper fruit preservation time, and nutrients were also determined. Soil nutrient parameters including organic matter and available NPK of treatments were assayed before and after one growth season. All of the mixture of BF+organic compost treatment significantly enhanced the yield and quality of pepper fruit. Moreover, disease control capacity was promoted by the mixture of BF+organic compost, with BF+SSV reaching the highest control efficacy of 81% on 60th day after transplanting, and remaining 76% at the 105^th day. The BF+SSV treatment showed soil fertility retention ability with higher soil nutrient contents after one growth season of pepper. This study provides evidence that, when combined with organic fertilizers such as spent mushroom substrate compost, beneficial microbes have the ability to promote plant growth and yield as well as suppress plant disease by sustaining soil fertility through complex bacteria–soil–plant interaction.     

Seasonal variation and low-cost agronomic practices effect growth and yield of moth bean (Vigna aconitifolia) in the extreme arid Thar desert

An experiment was laid out at Jaisalmer for three consecutive rainy seasons (2007 to 2009) to evaluate the effect of season and the efficacy of low-cost agronomic practices on the performance of moth bean (Vigna aconitifolia L.) in the extreme arid Indian Thar. Skip row planting (skipping every third row) significantly improved pods and seed weight per plant, and consequently seed yield, over normal planting. Total readily available water and moisture availability at critical growth stages of the crop significantly influenced plant attributes and thus biological and seed yield. Relative leaf water content (RWC) at sunrise in the pre- and post-flowering stages remained above the moisture stress level. However, at midday, plants experienced moderate stress in RWC during pre-flowering and severe stress during the post-flowering stages. Foliar application of 1% urea was found to be effective only when midday RWC is more than the critical threshold value of 84%. Therefore, foliar application of 1% urea at the pre-flowering stage significantly increased almost all plant attributes and yields, whereas second foliar application at post-flowering stage when midday RWC was <84% has no impact on plant attributes and yield.     

轮耕对渭北旱塬春玉米田土壤理化性状和产量的影响

为了揭示不同轮耕处理对渭北旱塬春玉米田土壤理化性状及春玉米产量的影响,于2008—2010年在陕西合阳设置了免耕深松免耕(NT/ST/NT)、深松翻耕深松(ST/CT/ST)、翻耕免耕翻耕(CT/NT/CT)、免耕免耕免耕(NT/NT/NT)、深松深松深松(ST/ST/ST)和翻耕翻耕翻耕(CT/CT/CT)6种轮耕模式,测定和分析了各轮耕处理下土壤容重、土壤养分与玉米产量差异。结果表明:(1)各轮耕处理降低了土壤容重,提高了土壤孔隙度,增加了田间持水量,且以NT/ST/NT处理效果最佳;与对照CT/CT/CT相比,NT/ST/NT处理0～20cm和20～40 cm土层土壤容重分别降低11.43%和9.79%,土壤孔隙度分别增加11.05%和9.87%。(2)NT/ST/NT处理对耕层0～20 cm土层土壤有机质和全氮含量影响显著(P<0.05),0～60 cm土层土壤有机质平均含量最高(10.36 g.kg 1),土壤全氮含量平均值比试验开始前和对照CT/CT/CT分别提高10.65%和4.31%;各耕作处理对0～20 cm土层土壤全氮和碱解氮含量影响较大,而对20～40 cm土层土壤有效磷和速效钾含量影响较大,保护性轮耕处理对土壤培肥效应显著(P<0.05)高于传统翻耕处理。(3)NT/ST/NT、ST/CT/ST、CT/NT/CT、NT/NT/NT和ST/ST/ST处理产量比对照CT/CT/CT处理分别增产22.42%、16.33%、3.77%、9.91%和14.18%(P<0.05),以NT/ST/NT处理春玉米增产率最高。     

Short-term effects of organo-mineral enriched biochar fertiliser on ginger yield and nutrient cycling

Purpose

Biochar has agronomic potential but currently is too expensive for widespread adoption. New methodologies are emerging to reduce the cost such as enriching biochar with nutrients that match crops and soil requirements. However, the effects of biochar-based fertilisers on plant yield and soil nutrient availability have not been widely examined. This study investigated the effects of a novel organo-mineral biochar fertiliser in comparison to organic and commercial biochar fertiliser on ginger (Zingiber officinale Canton).

Materials and methods

There were four treatments: (1) commercial organic fertiliser (5 t ha^?1), as the control; (2) commercial biochar-based fertiliser (5 t ha^?1); (3) organo-mineral biochar fertiliser at low rate (3 t ha^?1); and (4) organo-mineral biochar fertiliser at high rate (7.5 t ha^?1). A replicated pot trial was established with black dermosol soil and ten replicate pots for each treatment. Ginger was planted and grown for 30 weeks. Plant growth, biomass, foliar nutrients and water extractable soil nutrients including phosphorus (P), potassium (K) and calcium (Ca) were examined.

Results and discussion

High rate organo-mineral biochar fertiliser increased soil P and K availability at week 30 (harvest) after planting, compared to all other treatments and low rate organo-mineral biochar fertiliser performed similarly to the organic control for P and K. High rate organo-mineral biochar fertiliser increased total foliar nutrient content at week 30 in P, K and Ca compared to commercial biochar fertiliser. High rate organo-mineral biochar fertiliser improved the commercial value of ginger (+?36%) due to a shift in the proportion of higher grade rhizomes. Low rate organo-mineral biochar fertiliser plants displayed similar yield, total dry and aboveground biomass to commercial organic fertiliser. Commercial biochar fertiliser had significantly lower biomass measures compared with other treatments as the rate applied had lower nutrient concentrations.

Conclusions

Our results show organo-mineral biochar fertilisers could be substituted for commercial organic fertilisers at low rates to maintain similar yield or applied at high rates to increase commercial value where economically feasible.

     

土壤添加剂对德国卢萨蒂亚的台矿基质上作物产量和C收支的影响

Opencast lignite mining in the Lusatia region of Germany has resulted in large scale landscape disturbances,which require suitable recultivation techniques in order to promote plant growth and establishment in the remaining nutrient-poor substrates with low water-holding capacity.Thus,the effects of two commercial soil additives (CSA),a hydrophilic polymer mixed with volcanic rock flour and bentonite (a-CSA),and digester solids from biogas plants enriched with humic acids and bentonite (b-CSA),on soil organic carbon (SOC) storage,plant yields and root biomass were assessed after cultivating perennial crops (Dactylis glomerata L.) in monoculture and Helianthus annuus L.-Brassica napus L.in crop rotation systems.The CSA were incorporated into the top 20 cm soil depth using a rotary spader.The results indicated that a-CSA led to a significant increase in plant yield during the first year,and improved root biomass in the following year.As a result,SOC stocks increased,especially in the 0-10 cm soil layer.No significant sequestration of additional SOC was observed on b-CSA-amended plots at the end of both years.Bulk density values decreased in all treatments under the monoculture system.It can be concluded that application of a-CSA enhanced soil water availability for plant uptake and consequently promoted plant growth and organic carbon sequestration.The relative enrichment of organic matter without effects on water-holding capacities of b-CSA treatments suggested that it was not suitable for rapid land reclamation.     

不同土壤改良剂处理对连作西洋参根际微生物数量、土壤酶活性及产量的影响

以北京地区连作西洋参为研究对象, 通过3种土壤改良剂(熟石灰、EM菌剂、沼液)随机区组试验对其土壤理化性状、酶活性、根际微生物区系及产量进行了系统研究。结果表明: 低浓度熟石灰、中浓度EM菌剂及高浓度沼液处理最有利于提高西洋参产量; 施加熟石灰处理后, 土壤微生物主要类群数量显著减少, 土壤pH显著升高, 并对土壤脲酶活性有明显抑制作用; 施加沼液和EM菌剂处理后, 土壤有效微生物菌群显著增加(P<0.05), 土壤有机质和营养物质含量也显著增加(P<0.05), 并对土壤脲酶和多酚氧化酶活性有一定的促进作用。相关性分析发现, 土壤微生物主要类群的数量与蔗糖酶、脲酶、多酚氧化酶活性均有一定的相关性, 其中, 土壤细菌数量与蔗糖酶、多酚氧化酶活性呈极显著正相关(r分别为0.895^**和0.808^**), 土壤真菌和放线菌数量与蔗糖酶、脲酶、多酚氧化酶活性呈极显著正相关(r分别为0.932^**、0.769^**、0.840^**和0.837^**、0.891^**、0.797^**)。另外, 土壤细菌数量与有机质含量呈极显著正相关(r=0.863^**)。表明连作西洋参根际微生物区系及土壤酶活性与土壤理化性状之间紧密联系, 通过施加不同土壤改良剂, 可以为耐连作种植西洋参提供适宜的土壤环境。     

联合施用不同植物物质和鸡粪对土壤碳氮含量和蔬菜产量的影响

The use of plant materials as soil amendments is an uncommon practice amongst major farming communities in Ghana, although it is necessary for soil fertility improvement. An examination of the effects of soil amendments is necessary to encourage the use of under-utilized organic resources in Ghana. Thus, a field experiment was conducted using 8 different tropical plant materials mixed with chicken manure as soil amendments for growth of tomato as a test crop. The plant materials included Leucaena leucocephala, Centrosema pubescens, Sesbania sesban, Gliricidia sepium, Mucuna pruriens, Pueraria phaseoloides, Azadirachta indica, and Theobroma cacao. There were two other treatments: one with equivalent amounts of chemical fertilizers and the other with no-fertilizer input (control). Plant materials were mixed with chicken manure to obtain a uniform carbon-to-nitrogen (C:N) ratio of 5:1. Except the no-fertilizer control, all treatments received the same amount of nitrogen (N). To clarify the decomposition pattern of the plant materials in soil, an incubation experiment was conducted using only the plant materials before the field experiment. The Gliricidia treatment released significantly more mineral N than the other plant materials in the incubation experiment. However, the tomato fruit yield was not enhanced in the Gliricidia treatment in the field experiment. The known quality parameters of the tested plant materials, such as total N, total carbon (C), C:N ratio, and total polyphenols, had minimal effects on their mineralization dynamics. Azadirachta showed the best synergistic effect with chicken manure through significantly increasing soil microbial biomass and fruit yield of tomato. This result provides insights into the possible adoption of Azadirachta in combination with chicken manure as a soil amendment in small-scale agricultural holdings.     

秸秆还田对东北黑土碳氮磷钾化学计量特征及玉米产量的影响

【目的】秸秆还田是提升农田土壤肥力,改善土壤养分含量及有效性的重要措施。我们分析了东北黑土区不同秸秆还田方式下土壤碳氮磷钾含量和玉米产量的年际变化,并从土壤化学计量特征角度研究了土壤养分的有效性。【方法】依托2012年在东北黑土区建立的秸秆还田长期定位试验,选取秸秆移除(CK)、秸秆混合还入0—20 cm耕层(RI)和秸秆覆盖还田(RC) 3个处理,测定了处理实施1年(2013)、3年(2015)、5年(2017)和8年(2020)后,不同土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)含量及玉米产量,计算了土壤化学计量特征(C∶N、C∶P、N∶P),并分析了各指标之间的相关性。【结果】随试验年限的增加,在0—20 cm土层,CK处理SOC含量有所下降,TN含量基本保持不变,而RI和RC处理的SOC和TN含量均有所增加,RC处理下均为最高;RI处理的SOC和TN含量在0—20 cm土层分布相对均匀,RC处理SOC和TN含量在0—5 cm土层中明显增加,尤其在试验5～8年间的增幅明显升高。CK、RI和RC 3个处理的TP和TK含量均随试验年限的增加缓慢升高,处理间无显著...     

Biochar combined with magnesium fertilizer improves cabbage (Brassica oleraceae L.) yield by modulating physicochemical characteristics and the bacterial community in acidic soil

Biochar and magnesium (Mg) fertilizers have gained increasing attention in agriculture for their potential benefits. However, their combined effects on vegetable growth in southern acidic soils have not been fully elucidated. To address this issue, a study was conducted with six treatments all of which included a baseline amount of compound fertilizer (CK), an increased amount of compound fertilizer (F), Mg fertilizer (M), biochar (BC), biochar combined with Mg (BCM) and an increased amount of compound F with Mg (FM), to investigate their synergistic effects on soil physicochemical properties, enzyme activity, microorganisms and cabbage yield. The results of the study showed that compared with CK, the M, BC and BCM treatments all increased soil organic matter (SOM), exchangeable magnesium (Ex-Mg), acid phosphatase (ACP) and yield, while the F treatment led to a 5% decrease in SOM. The BCM treatment significantly increased SOM, Ex-Mg, ACP by 14%, 40%, and 25%, respectively. The most abundant phyla in BCM processing were Proteobacteria (21%), Chloroflexi (19%) and Actinomycetes (17%); the most abundant genera were Bacillus (8%). Further, the effect of BCM on crop growth promotion was better than that of FM, and the economic analysis showed that compared with FM, the benefit of BCM increased by 14%. Through structural equation modelling analysis, the synergistic increase in yield was because of the increase in soil TP, Ex-Mg, NO₃⁻–N and β-GC caused by BCM, improving soil nutrients and microbial communities, thereby promoting cabbage growth. Therefore, the combined application of biochar and Mg in acidic soil could significantly improve soil fertility and crop productivity, while also reducing the need for costly chemical fertilizers, thereby offering a promising and cost-effective approach for sustainable agriculture.     

Fertigation of humic substances improves yield and quality of broccoli and nutrient retention in a sandy soil

There is lack of information available concerning the effect of humic substances (HS) applied via fertigation on plant growth in sandy soils. Therefore, a field experiment was carried out at El‐Saff district (20 km southwest of Cairo), Egypt, to investigate the role of HS fertigation on water retention of a sandy soil, yield and quality of broccoli (Broccoli oleracea L.) as well as on soil nutrient concentration retained after harvest. The experiment consisted of six fertigation treatments (50%, 75%, and 100% of the recommended NPK‐fertilizer rate for broccoli combined with and without HS application at 120 L ha^–1) in a complete randomized block design with three replicates. Humic substances affected spatial water distribution and improved water retention in the root zone. Furthermore, application of HS increased total marketable yield and head diameter of broccoli as well as quality parameters (i.e., total soluble solids, protein, and vitamin C). Higher nutrient concentrations were found in the broccoli heads and concentrations of plant‐available nutrients in soil after harvesting were also higher, indicating an improvement in soil fertility. In conclusion, HS fertigation can be judged as an interesting option to improve soil water and nutrient status leading to better plant growth.     

旱地垄沟覆膜栽培对土壤硝酸盐时空分布和玉米产量的影响

通过大田试验,考察了旱地垄沟覆膜栽培对土壤硝酸盐时空分布和玉米生物性状及产量的影响。试验设计了垄沟覆膜、平作不覆膜、平作覆膜和裸地对照4个处理,并对其土壤水分、硝酸盐的时空分布和玉米产量进行研究。结果表明:在整个玉米生长季,垄沟覆膜栽培模式下土壤0~40 cm土层含水量显著高于平作不覆膜;NO_3~--N主要集中在0~40 cm土层,且垄沟覆膜-垄上NO_3~--N表聚现象比其它处理更明显,10 cm处垄上NO_3~--N含量是沟内的1.6倍、平作不覆膜的2倍;垄沟覆膜和平作覆膜比平作不覆膜处理单株干物质量分别增加了36.15%、16.11%;单株含氮量分别增加了13.97%、3.59%;垄沟覆膜产量高于其他处理。垄沟覆膜栽培能够在保持作物生长状况良好,获得较高产量的同时,增加作物对氮素的吸收利用,同时增加NO_3~--N的表层累积,将其保持在根区,从而降低了NO_3~--N淋洗的发生,降低环境风险,是旱区获得经济和环境双重效益的玉米栽培模式。     

Plant availability of heavy metals in a soil amended with a high dose of sewage sludge under drought conditions

The objective of this research was to study the effect of water deficit on soil heavy metal availability and metal uptake by ryegrass (Lolium multiflorum Lam.) plants grown in a soil amended with a high dose of rural sewage sludge. Three fertility treatments were applied: sewage sludge (SS), mineral fertilizer (M), and control (C); unamended). The levels of irrigation were: well-watered (W) and water deficit (D). Microbial respiration decreased the total organic C (TOC) in sludge-treated soils, but this did not enhance soil DTPA-extractable heavy metal concentrations. Indeed, Zn, Cu, Mn and Ni availability decreased during the experiment. C- and M-treated soils showed either no changes or increases of some trace element concentrations during the incubation. In the plant experiment, ryegrass dry matter (DM) yield, relative water content (RWC) and leaf water potential (_w) decreased in drought conditions. Sludge addition increased metal concentrations in plants. However, in some instances, SS-treated plants showed either similar or lower transfer coefficient (Tc) values than did plants in the C and M treatments. Water deficit decreased the concentration and the Tc of some metals in roots of M and SS plants. Results indicate that sludge-borne heavy metals were maintained in chemical forms of low availability. The lower metal uptake by SS and M plants under dry conditions cannot be attributed to a lower availability of these elements in soil.     

Within plot variability in available soil mineral nitrogen in relation to leaf greenness and yield

Abstract

Available soil mineral nitrogen (N) varies both temporally and spatially. These variations affect field‐scale N‐use efficiency. A field study was conducted for three years to investigate spatial variability in available soil mineral N within uniform research plots in relation to leaf greenness or chlorophyll content (plant N sufficiency) and yield. Variations within the plot in available soil mineral N sampled at the 6‐ligule stage was related to N fertility: the higher the fertilizer N levels, the higher the variability. The standard deviation for the 200 kg N ha^‐1 treatment was up to five times higher than the unfertilized control treatment. The nitrate (NO₃)‐N accounted for 70 to 80% of soil mineral N in fertilized plots compared to 50 to 60% in unfertilized control plots. The variability in grain yield of individual maize (Zea mays L.) plants within a plot was inversely related to soil N fertility: the higher the fertilizer N levels, the lower the yield variability (at 100 or 200 kg N ha^‐1, yield ranged from 97 to 148 g plant¹, or 10% CV within ayear compared to ranges from 0 to 82, or 50% CV in the same year at 0 kg N ha^‐1). On an individual plant basis, chlorophyll content from the 6‐ligule stage through the growing season generally showed much smaller CV's, but had a similar trend to variations in yield. Leaf greenness from 6‐ligule stage to silking was significantly correlated with harvest yield (r>0.60, P<0.01), and both also correlated with available soil mineral N, though to a lesser degree (r>0.36). The number of fully expanded leaves prior to silking differentiated N treatments better than did single leaf chlorophyll measurements with higher yields associated with more rapid vegetative development. Our data suggest that multiple core samples are required to estimate available soil mineral N, particularly in fertilized plots that have greater spatial variability. Variability of plant‐based measures, such as chlorophyll content, could be used as an indicator of relative plant N sufficiency at early growth stages as spatial variability declined with higher soil N fertility.     

宁南旱区沟垄覆盖改善土壤水热状况提高马铃薯产量

垄覆塑料地膜沟内覆盖集雨种植模式可影响土壤水热状况,促进作物生长,提高作物的产量和水分利用效率。为探讨旱作条件下沟垄二元覆盖的土壤水热效应对马铃薯产量的影响效果,于2015年在宁南旱区设置垄覆地膜沟内覆盖不同材料(普通塑料地膜、玉米秸秆、生物降解膜、麻纤维地膜及液态地膜),以垄覆地膜沟不覆盖为对照,研究沟垄二元覆盖模式对土壤水分、耕层土壤温度、马铃薯生长、产量及水分利用效率的影响。结果表明:垄覆地膜沟覆地膜处理在马铃薯前期、中期土壤蓄水量较对照显著增加(P0.05),垄覆地膜沟覆秸秆处理在马铃薯生育后期土壤蓄水量最高(P0.05)。垄覆地膜沟覆地膜处理增温效果明显,马铃薯全生育期0~25 cm土壤温度较对照显著增加(P0.05),而垄覆地膜沟覆秸秆处理较对照显著降低(P0.05)。在马铃薯整个生育期,垄覆地膜沟覆秸秆处理植株株高和茎粗均明显高于对照处理(P0.05),在马铃薯生育后期垄覆地膜沟覆秸秆处理的地上部生物量显著高于对照处理(P0.05)。沟垄二元覆盖模式下马铃薯增产效果以垄覆地膜沟覆秸秆处理最为显著,较对照增产56.1%(P0.05),且水分利用效率最高(81.1kg/(hm2·mm))。总之,垄覆地膜沟覆秸秆处理对改善土壤水热状况,提高马铃薯水分利用效率和产量的效果显著,建议在宁南旱区进行推广应用。