有机无机肥配施对滨海脱盐土栽培菊芋及其养分吸收的影响

以蚯蚓粪和无机复合肥为材料,设置CK(不施肥)、T1(无机复合肥300kg/hm²)、T2(无机复合肥600kg/hm²)、T3(蚯蚓粪7.5 t/hm²)、T4(蚯蚓粪7.5 t/hm²、无机复合肥300 kg/hm²)、T5(蚯蚓粪7.5 t/hm²、无机复合肥600 kg/hm²)、T6(蚯蚓粪15 t/hm²)、T7(蚯蚓粪15 t/hm²、无机复合肥300 kg/hm²)、T8(蚯蚓粪15 t/hm²、无机复合肥600 kg/hm²)共计9个处理,研究了蚯蚓粪和无机复合肥配施下滨海脱盐土土壤性质的变化,栽培菊芋生长特性及养分吸收规律,以确立滨海脱盐土菊芋高效栽培最适有机无机肥配施方案。结果表明：随菊芋生育进程推进,土壤可溶性盐含量下降,T6处理幼苗期和开花期的可溶性盐含量均最低,分别为0.28和0.29 g/kg,较...     

The Maturity and CH4, N2O,NH3 Emissions from Vermicomposting with Agricultural Waste

This study investigated the maturity and gaseous emissions from vermicomposing with agricultural waste. A vermicomposting treatment (inoculated Eisenia fetida) was conducted over a 50-day period, taking tomato stems as the processing object and using cow dung as the nutrient substrate. A thermophilic composting treatment without earthworm inoculation was operated as a control treatment. During the experiment, maturity indexes such as temperature, pH, C/N ratio, and germination index (GI) were determined and continuous measurements of earthworm biomass and CH₄, N₂O, and NH₃ emissions were carried out. The results showed that the temperature during vermicomposting was suitable for earthworm survival, and the earthworm biomass increased from 10.0 to 63.1 kg m^?3. Vermicomposting took less time on average to reach the compost maturity standard (GI 80%), and reached a higher GI (132%) in the compost product compared with the thermophilic composting treatment. Moreover, the decrease of the C/N ratio in vermicompost indicated stabilization of the waste. The activities of earthworms played a positive role in reducing gaseous emissions in vermicompost, resulting in less emissions of NH₃ (12.3% NH₃-N of initial nitrogen) and total greenhouse gases (8.1 kg CO₂-eq/t DM) than those from thermophilic compost (24.9% NH₃-N of initial nitrogen, 22.8 kg CO₂-eq/t DM). Therefore, it can be concluded that vermicomposting can shorten the period required to reach compost maturity, can obtain better maturity compost, and at the same time reduce gaseous emissions. As an added advantage, the earthworms after processing could have commercial uses.     

高温处理与添加物料对蚓粪基质培育辣椒壮苗的影响

蚓粪是蚯蚓处理有机固体废弃物的产物,具备替代泥炭作为蔬菜育苗基质材料的优良性质。蚓粪高温处理（120℃）后加入蛭石、 尿素等物料复配成育苗基质,通过温室育苗和室内分析的手段,分析蚓粪中活性有机物和GA3、 IAA的含量变化以及蚓粪基质培育辣椒幼苗的系统发育特征。结果表明, 蚓粪高温处理过程增加了蚓粪中GA3含量,使活性有机物裂解成具有相同母核类极性更大的水溶性衍生物。无论是否高温处理,蚓粪育苗基质都有利于辣椒幼苗茎粗、 株高、 展宽、 叶片数、 根长、 根表面积、 根体积、 根尖数、 鲜（干）重和壮苗指数的提高,但会导致辣椒幼苗叶片叶绿素含量的减小。蚓粪添加蛭石和高温处理后育苗能够增大辣椒幼苗根直径。高温处理蚓粪中添加蛭石（蚓粪∶蛭石=4∶1,V∶V）和尿素（0.50 kg/m3）有利于提高辣椒幼苗成苗率,增加鲜干物质累积,促进茎叶和根系的系统发育,增大壮苗指数。可见,蚓粪高温处理后与蛭石按4∶1体积比均匀混合后用于辣椒育苗,最能提升辣椒幼苗的各项指标,形成壮苗。     

IDENTIFICATION OF OPTIMUM COMBINATION OF PROPORTION OF VERMICOMPOST IN THE SOIL-BASED POTTING MIX AND POT VOLUME FOR THE PRODUCTION OF PAPER POT SEEDLINGS OF VEGETABLES

An investigation was conducted to identify the best combination of proportion of vermicompost in soil-based potting mix and pot volume for the production of paper pot seedlings suitable for mechanical transplanting. The best combination of the potting mix and pot volume is the one that produces seedlings with high growth of root and shoot biomasses at the end of seedling stage, low in cost and light in weight. Cubical shaped paper pots of 50 cm³ volume filled with potting mix of 25% vermicompost and 75% soil and sand in equal proportion by volume was found to be best for the large scale production of paper pot seedlings of tomato, eggplant, and chili peppers. The paper pots were found to be firm at the end of seedling stage and variations in their dimensions could be accommodated in fully automatic transplanters with horizontal chain conveyor type seedling feeding and metering devices.     

移栽定殖根际有益菌番茄苗的田间效应研究

为评估移栽定殖根际有益菌(PGPR)番茄苗对果实产量和青枯病防控效果的影响,通过连续3季田间试验,研究了基于生物有机肥的施用,移栽生物育苗基质(在普通育苗基质中添加分离自根际的解淀粉芽孢杆菌)所育种苗(BIONS),相比于移栽普通育苗基质所育种苗(BIO),对设施番茄产量、发病率、收获期植株土体与根际微生物数量和土壤基本理化性质的影响。连续3季田间试验结果表明:相比于BIO处理,BIONS处理第一、二、三季的增产幅度分别达38.86%、47.87%、34.60%,产量差异均达到显著性水平;BIONS处理的发病率每季均极显著低于BIO处理;BIONS处理增加了根际细菌数量,降低了根际真菌数量;土壤基本理化性质方面,BIONS处理的硝态氮含量和铵态氮含量每季均高于BIO处理,且硝态氮含量与产量呈显著正相关,硝态氮含量和铵态氮含量与发病率呈显著负相关。因此,以生物有机肥为底肥,移栽生物育苗基质所育种苗,能够有效防控番茄青枯病的发生,进而提高产量。     

模拟氮沉降对一年生香椿幼苗生长和光合特性的影响

为研究氮沉降对一年生香椿(Toonasinensis)幼苗夏季生长以及光合特性的影响,通过在夏季模拟氮沉降控制试验,以尿素为氮源供体,设置0kg(N)×hm~(-2)×a~(-1)(CK)、20kg(N)×hm~(-2)×a~(-1)、40kg(N)×hm~(-2)×a~(-1)、80kg(N)×hm~(-2)×a~(-1)、120 kg(N)×hm~(-2)×a~(-1)、180 kg(N)×hm~(-2)×a~(-1)不同氮添加水平以模拟氮沉降,对香椿幼苗地径、苗高、生物量及其分配和光合作用等进行研究。结果表明:1)不同氮添加量均促进了香椿幼苗地径、苗高和生物量的增加,地径、苗高和生物量均以氮添加水平180kg(N)×hm~(-2)×a~(-1)下最高,分别较CK高42.5%、64.4%和304.9%,且生物量向根、叶分配较多; 2)香椿幼苗叶片相对叶绿素含量(SPAD)随氮添加水平的增加而增加,在180 kg(N)×hm~(-2)×a~(-1)下最高,较CK增加73.9%;3)香椿幼苗表观量子效率(AQY)、最大净光合速率(Pnmax)、光饱和点(LSP)、光补偿点(LCP)以及暗呼吸速率(Rd)随氮添加水平的增加均呈现先升高后降低的趋势,其中LCP以80 kg(N)×hm~(-2)×a~(-1)下最高, AQY、Pnmax、LSP和Rd均以120kg(N)×hm~(-2)×a~(-1)下最高。结果表明,适量氮沉降能够促进香椿幼苗生长和光合能力的提高,但更高水平的氮沉降可能对香椿幼苗产生一定抑制作用。     

Comparative Effect of Nitrogen Forms on Nitrogen Uptake and Cotton Growth Under Salinity Stress

The effects of nitrogen (N) forms (ammonium- or nitrate-N) on plant growth under salinity stress [150 mmol sodium chloride (NaCl)] were studied in hydroponically cultured cotton. Net fluxes of sodium (Na⁺), ammonium (NH₄⁺), and nitrate (NO₃^?) were also determined using the Non-Invasive Micro-Test Technology. Plant growth was impaired under salinity stress, but nitrate-fed plants were less sensitive to salinity than ammonium-fed plants due mainly to superior root growth by the nitrate-fed plants. The root length, root surface area, root volume, and root viability of seedlings treated with NO₃-N were greater than those treated with NH₄-N with or without salinity stress. Under salinity stress, the Na⁺ content of seedlings treated with NO₃-N was lower than that in seedlings treated with NH₄-N owing to higher root Na⁺ efflux. A lower net NO₃^? efflux was observed in roots of nitrate-fed plants relative to the net NH₄⁺ efflux from roots of ammonium-fed plants. This resulted in much more nitrogen accumulation in different tissues, especially in leaves, thereby enhancing photosynthesis in nitrate-fed plants under salinity stress. Nitrate-N is superior to ammonium-N based on nitrogen uptake and cotton growth under salinity stress.     

蚯蚓堆肥用作苹果育苗基质的应用研究

本研究采用穴盘栽培的方式,以不同比例的蚯蚓堆肥替代草炭调配育苗基质配方,用于苹果的育苗效果研究,通过比较苹果苗生长状况,以为蚯蚓堆肥在果树育苗上的应用提供参考。试验设置4个处理,包括传统草炭基质处理(对照)、蚯蚓堆肥25%、50%、100%替代草炭基质处理,对苹果苗的株高、茎粗、叶片光合色素含量、壮苗指数、根系形态和根系活力指标进行测定和分析。结果发现:与对照相比,蚯蚓堆肥不同比例替代草炭(25%、50%、100%)均能够增加苹果苗的地上生物量,以全替代(100%)的效果最为显著,全替代处理下苹果苗的存活率提高了15%,根系长度、根表面积、根体积、根尖数、根干重和根系活力分别增加了23.40%、47.61%、5.88%、38.57%、20.17%、228.75%。因此,蚯蚓堆肥可以全替代草炭用作苹果苗的育苗基质,且不仅能够降低成本,还可以促进农业废弃物的循环转化,降低环境风险。     

腐植酸对番茄苗期氮素代谢的影响

腐植酸对肥料具有改性增效的作用,以番茄为供试材料,研究腐植酸增效剂不同添加量对番茄苗期生长及氮素代谢酶活性的影响,为腐植酸的开发应用提供参考依据。采用砂培试验方法,设置了向霍格兰营养液分别加入腐植酸增效剂0(HA0),1(HA1),2(HA2),5(HA3),10(HA4) mL/L处理。培养30天后,测定番茄的生长指标、植株养分含量、硝酸还原酶活性、谷氨酰胺合成酶和谷氨酸脱氢酶活性。添加适量腐植酸增效剂能促进番茄苗期生长,HA3处理番茄根系干重比HA0提高了31.68%,HA1处理番茄地上部干重最大。添加腐植酸可以提高番茄苗期叶片叶绿素含量,HA3处理番茄苗期叶片叶绿素总量和类胡萝卜素含量最高,分别比HA0提高了17.11%,24.04%。添加适量腐植酸增效剂能增加番茄苗期根系和地上部对氮素的吸收,HA3处理的番茄根系、地上部及总氮素积累量比HA0分别提高了30.61%,20.24%,21.54%。添加腐植酸增效剂可以调控番茄根系和叶片氮素代谢过程,提高了氮素代谢酶活性,与HA0相比,HA4处理根系硝酸还原酶活性最大,HA3处理根系谷氨酰胺合成酶活性最高,HA2处理根系谷氨酸脱氢酶的活性最大;HA3处理番茄苗期叶片中硝酸还原酶、谷氨酰胺合成酶和谷氨酸脱氢酶活性最大,与HA0处理相比分别提高了38.27%,64.54%,106.63%。添加腐植酸增效剂可以促进番茄苗期的生长和对氮素的吸收,提高氮素代谢酶活性,处理中以在营养液中添加5 mL/L腐植酸增效剂效果最佳,腐植酸增效剂添加量低于5 mL/L时,对番茄苗期的生长及氮素代谢具有明显的促进作用。     

日光温室番茄灌水量与根层硝态氮淋溶特征及渗漏关系研究

针对蔬菜灌溉水肥渗漏问题,采用田间试验和室内分析相结合,研究了番茄膜下沟灌灌水量与土壤硝态氮的根层外渗漏关系,分析了灌水量与不同根层土壤硝态氮的淋溶和保蓄特征,结果表明:灌溉不施肥条件下灌水量与土壤硝态氮淋溶量和淋溶率、灌溉施肥条件下灌水量与土壤施入硝态氮的保蓄率和渗漏率均呈直线关系;灌溉均会引起浅根层(0—20 cm)硝态氮淋溶,灌溉施肥条件下7.5～15 mm灌水量范围硝态氮积累有一个峰值,而22.5～45 mm范围则有两个峰值;灌水量在7.5～15mm之间,灌溉不施肥条件下根层土壤硝态氮淋溶率为0,灌溉施肥条件下土壤硝态氮渗漏率为0～5.19%;灌水量在22.5～45 mm之间,灌溉不施肥土壤硝态氮淋溶率为5.38%～19.08%,灌溉施肥条件下根层土壤硝态氮渗漏率为21.91%～61.96%。日光温室番茄膜下沟灌能减少肥料淋溶与渗漏的节水灌水量为15 mm。     

不同pH和不同氮素形态对小麦根中钙分布的影响

利用电镜技术研究了不同pH(4.0和6.0)和氮形态(NH4+-N和NO3---N)对小麦根系超微结构及根中Ca2+分布的影响。结果表明,1)pH.4.0处理下细胞结构中Ca2+明显少于pH.6.0处理;2)低pH造成质壁分离;3)铵态氮源处理下细胞结构中Ca2+明显少于硝态氮源处理,尤其体现在细胞间质、细胞壁、细胞膜上;4)铵态氮源处理也会导致细胞出现质壁分离,细胞结构松散,胞质外流;低pH加重这些现象。     

Studies on the Effects of Vermicompost on Physicochemical Properties and Growth of Two Tomato Varieties under Greenhouse Conditions

This research was conducted to investigate effects of different vermicompost rates on breeding quality and growth of two tomato varieties. Six treatments were applied, combining vermicompost (VC) with rice husk ash (RHS) and coconut fiber (CF) with the following proportions: 3/3 VC (control treatment, T1), 2/3 VC + 1/3 RHS (T2), 2/3 VC + 1/3 CF (T3), 1/3 VC + 2/3 RHS (T4), 1/3 VC + 2/3 CF (T5), and 1/3 VC + 1/3 RHS + 1/3 CF (T6). The results demonstrated that there was significant difference between combining VC, RHS, and CF into EC and combining those into macronutrients of substrates with increasing VC mixture proportion; however, water-holding capacity (WHC), zinc (Zn), manganese (Mn), and iron (Fe) contents were significantly increased with reduced VC mixture proportion. A mixture of VC with RHS and CF made with the rate of 1:1:1 significantly influenced emergence and elongation of seedlings of both varieties. Biomass allocation was affected by VC amendments for two varieties in seedling stage and one field-grown tomato variety. The VC amendment did not affect the phosphorous (P), Fe, and Zn contents but significantly influenced nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), and Mn concentrations in the shoots. The mixture of VC with RHS and CF made with the rate of 1:1:1 was found to provide optimum conditions for seedling performance of the two tomato varieties.     

秋葵连作土壤浸提液对番茄生长的障碍研究

单一耕作制度和作物品种，使设施连作障碍日益加剧。番茄和秋葵都是重要的设施蔬菜类型，但种植发现秋葵对番茄存在生长障碍，研究秋葵对番茄的生长障碍发生的生理生态机制具有重要意义。本研究选取种植秋葵的1 a和10 a土壤浸提液（简称1 a浸提液和10 a浸提液），以全素营养液为对照（简称CK），探讨秋葵连作土壤浸提液对番茄萌发期种子和幼苗生长的影响。结果表明：同一浓度土壤浸提液处理下，10 a浸提液的番茄萌芽期种子表现出主根畸形，侧根增多但细弱；番茄幼苗分根增多，根系活性低于1 a浸提液且都显著低于CK，顶部嫩叶失绿异常，活性氧代谢系统紊乱。同一年限不同秋葵土壤浸提液浓度处理下，番茄萌发期种子随浸提液浓度的升高表现出主根畸形，侧根增多且细弱，番茄幼苗分根增多，1 a和10 a浸提液的番茄根尖数、分根数分别最高达1 146、3 321和2 291、1 947，显著高于对照（1 071、385）；秋葵土壤浸提液浓度高于250 mg·mL^-1处理下番茄幼苗根系活性都显著低于CK，顶部嫩叶失绿异常，活性氧代谢系统紊乱。研究表明秋葵根系物及分泌物在土壤中残留，对后茬番茄的生长造成不良影响，这些物质随种植年限增加而富集，从而对番茄产生更严重的毒害。     

The role of phosphorus in growing tomatoes in near water-saturated soil

Abstract

High-yielding, waterlogged cultivations with considerable nitrogen input are widely practiced in Kyushu Island, Japan. Our objective was to determine the role of available phosphorus in relation to nitrogen and soil microorganisms on tomato growth in such systems. Tomato seedlings were grown in a pasteurized soil with ample KNO₃ in addition to different amounts of sodium or potassium phosphates to assess effects of phosphorus on growth enhancement and water-use efficiency in the seedlings grown with copious soil water (>－0.7?kPa). Both monobasic and dibasic phosphates applied at 40?mM to near-saturated soil markedly promoted seedling growth when fertilized with 120?mM KNO₃ or NH₄Cl, but not in the soil without nitrogen. The final concentration of NO₃^－ near the soil surface was maximized in the nitrated soil with no added PO₄^3－ but declined significantly when fertilized with any phosphates except Na₂HPO₄. No significant accumulation of NO₃^－ was detected in the water-saturated bottom soils regardless of soil fertilization with any plant minerals. Increased seedling growth was accompanied by lower dry root/shoot ratios and marked increases in evapotranspiration efficiency. Such positive effects of PO₄^3－ were greater with NO₃^－ than NH₄^＋ but diminished with increased concentrations of Na^＋ up to 160?mM. Nonetheless, growth promotions by ample NO₃^－ with PO₄^3－ were nearly negated in the non-pasteurized soil. Apparently, the activities of indigenous soil microbes were more significant than soil nitrogen and phosphorus in limiting the growth potential of tomato plants in near-saturated soils.     

Isotopic evaluation of the role of arbuscular mycorrhizae in the nitrogen preference in Chinese fir seedlings

Chinese fir seedlings grow well in shrubland (including deciduous forest) soils without or less fertilizer application, but they sometimes harbor disease and show symptoms of nitrogen deficiency in ploughed (including several rotation of Chinese fir plantation) soils, where agricultural practice and clear-felling reduce the abundance and diversity of mycorrhizal fungi, and lead to destruction of mycorrhizae. Based on measurements of foliar δ¹⁵N or foliar δ¹⁵N_fol-soil in seedlings collected from 33 nurseries, we compared the effect of an AM-mediated process on nitrogen resource use between shrubland and ploughed soils. In mycorrhizal seedlings growing in shrubland soils, both foliar δ¹⁵N and foliar δ¹⁵N (fol-soil) were significantly higher than those in ploughed soils, likely because of enhanced high δ¹⁵N/NO₃^? absorption through AM-mediated pathways. Those results showed that foliar δ¹⁵N typically reflected the isotopic signature of the source pools of N. We suggest that the dominant N form taken up by fir seedlings growing in ploughed soils was NH₄⁺-N rather than NO₃^?-N, where colonized root epidermis play an important role in exploiting soil N resource. However, the N form taken up by fir seedling growing in shrubland soils was primarily NO₃^?-N compared to NH₄⁺-N, which is attributed to the high efficiency in an AM-mediated process rather than the dominance of N species in the different habitats. It is conceivable that combined colonized root epidermis with AM-mediated process may be more important than root epidermis alone in exploiting different forms of N in nursery soils. Therefore, in low N and acidic ecosystems, species other than the dominant N-NH₄⁺, should be considered to satisfy the N demand for Chinese fir survival and growth, while the efficiency of an AM-mediated process should be determined by soil abiotic conditions.     

增苗节氮对早稻抛秧群体生物学特性及产量的影响

本研究在大田裂区试验下比较了3个氮肥水平[N1:105 kg·hm·2(节氮)、N2:135 kg·hm·2(节氮)、N3:165 kg·hm·2(常氮)]和3个抛秧密度[M1:27万穴·hm·2(常苗)、M2:31.5万穴·hm·2(增苗)、M3:36万穴·hm·2(增苗)]对‘湘早籼45号’抛秧群体生物学特性和产量的影响。结果表明:增苗节氮处理(N2M3)为产量最高的组合。株高、生育期受氮肥影响较大,密度影响不显著,N1比N3和N2的生育期分别延长7.0 d和3.4 d;氮肥、密度的增加对分蘖表现为相反的趋势,总体表现为茎蘖数随施氮量增加而增加,随密度增加而减少。通过对氮肥、密度与产量间进行二次多项式回归分析可知,产量最大值点Y=8.60 t·hm·2,对应施氮量为X1=127.5 kg·hm·2,密度为X2=48.0万穴·hm·2,其比常氮(165 kg·hm·2)节省氮肥22.7%。表明早稻抛秧可以通过增苗来弥补节氮所带来的产量损失,早稻施氮量和抛秧密度搭配时应该以"增苗节氮"为原则。最佳施氮量在127.5~135 kg·hm·2,最佳抛秧密度在36~48万穴·hm·2。综上所述,双季抛秧的季节性矛盾能通过早稻"增苗节氮"来解决,有利于减少环境污染,延缓农业生态系统水体富营养化。     

Nitrogen and vermicompost interaction on soil and leaf nutrient status of kinnow mandarin in vertisols of Jhalawar district

A field experiment entitled “nitrogen and vermicompost interaction on soil and leaf nutrient status of kinnow mandarin in vertisols of Jhalawar district” was conducted at the Fruit Research Farm, Department of Fruit Science, College of Horticulture and Forestry, Jhalawar (Rajasthan) during 2012–13 to study the effect of different levels of nitrogen and vermicompost on physico-chemical properties of soil and leaf micro and macro nutrient contents of Kinnow mandarin. The result indicated that application of T₁₅ treatment i.e. nitrogen at 350 g/plant + vermicompost 20 kg/plant was found best with regard to improvement in soil physico-chemical properties like organic carbon content (0.44%), available nitrogen (N) (379.36 kgha^?1), available phosphorus (P) (25.56 kgha^?1), available potassium (393.29 kgha^?1) and reduces electrical conductivity (0.34 dSm^?1), soil pH (7.42) and calcium carbonate (CaCO₃) content percentage (15.20) of soil.     

二氧化碳施肥对番茄幼苗生长与养分吸收利用的影响

Exposing tomato seedlings to elevated CO2 concentrations may have potentially profound impacts on the tomato yield and quality. A growth chamber experiment was designed to estimate how different nutrient concentrations influenced the effect of elevated CO2 on the growth and nutrient uptake of tomato seedlings. Tomato (Hezuo 906) was grown in pots placed in controlled growth chambers and was subjected to ambient or elevated CO2 (360 or 720 μL L-1), and four nutrient solutions of different strengths (1/2-, 1/4-, 1/8-, and 1/16-strength Japan Yamazaki nutrient solutions) in a completely randomized design. The results indicated that some agricultural characteristics of the tomato seedlings such as the plant height, stem thickness, total dry and fresh weights of the leaves, stems and roots, the G value (G value = total plant dry weight/seedling age),and the seedling vigor index (seedling vigor index = stem thickness/(plant height × total plant dry weight) increased with the elevated CO2, and the increases were strongly dependent on the nutrient solution concentrations, being greater with higher nutrient solution concentrations. The elevated CO2 did not alter the ratio of root to shoot. The total N, P, K, and C absorbed from all the solutions except P in the 1/8- and 1/16-strength nutrient solutions increased in the elevated CO2 treatment. These results demonstrate that the nutrient demands of the tomato seedlings increased at elevated CO2 concentrations.     

自然降雨下玉米秸秆堆沤还田对滇中小流域坡耕地氮素流失的影响

为探究自然降雨下不同堆沤方式秸秆还田对小流域坡耕地径流泥沙及氮素流失的影响,以滇中二龙潭流域坡耕地为研究对象,设置9种不同玉米秸秆堆沤方式,分别为CK及8种处理,各处理包括2种秸秆还田量(0.75,1.5 kg/m^2)、2种秸秆粒度(1,5 cm)、2种秸秆堆沤方式(水或水与尿素堆沤),研究烤烟坡耕地产流产沙及氮素流失特征。结果表明:(1)在4场具有典型产流的降雨中,施用较高秸秆还田量(1.5 kg/m^2)和粗颗粒秸秆(5 cm),均可有效减少坡耕地产流产沙量(10.06%~38.60%和10.07%~38.60%);(2)施用较低秸秆还田量(0.75 kg/m^2)、粗颗粒秸秆(5 cm)及未添加尿素堆沤的秸秆径流TN、NO3--N浓度低于施用高秸秆还田量(1.5 kg/m^2)、细颗粒秸秆(1 cm)及添加尿素堆沤的处理(1.96%~32.79%和3.97%~40.89%);(3)各处理下NO3--N/TN、NH4+-N/TN、PN/TN分别为63.64%~86.18%,5.31%~13.86%和5.33%~25.80%,表明坡耕地地表径流氮素主要流失形式为NO3--N,溶解态氮是径流中的主要氮素污染物;(4)施用较低秸秆还田量(0.75 kg/m^2)、粗颗粒(5 cm)秸秆、未加尿素堆沤的秸秆,泥沙TN流失浓度降低(16.87%~48.15%);(5)施用较高秸秆还田量、粗颗粒秸秆及未添加尿素堆沤可有效降低滇中坡耕地氮素的流失风险(0.32%~35.05%和54.52%~77.23%)。TN径流和泥沙流失中,以径流输出为主,占TN流失量的50.09%~71.67%。为了减少该流域氮素流失量,可选择施用较高秸秆还田量(1.5 kg/m^2)和粗颗粒(5 cm)秸秆,并依据烤烟不同生长期的吸收情况和土壤养分情况等选择少量或不添加尿素堆沤进行秸秆还田。     

施氮与灌水对夏玉米土壤硝态氮积累、氮素平衡及其利用率的影响

通过田间裂区试验研究了不同施氮量(N 0、150、210和270 kg/hm2)和灌水量(900、1200、和1500 m3/hm2)对夏玉米土壤硝态氮分布累积、氮素平衡以及氮肥利用率的影响。结果表明,夏玉米收获期各处理土壤硝态氮在表层(0—20 cm)含量最高,在0—200 cm剖面均呈现先减少后增加再减少的变化趋势;土壤剖面NO3--N累积量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理。作物吸氮量、氮素表观损失量均与施氮量和总氮输入量呈显著相关,氮素输入量每增加1 kg,作物吸氮量仅增加0.301 kg,而表观损失量增加0.546 kg,是作物吸氮量的1.8倍左右。随施氮量的增加土壤剖面中NO3--N的损失量逐渐减少。夏玉米子粒吸氮量和收获指数随施氮量的增加有增加的趋势;氮肥回收效率和氮肥农学效率均以处理W1500N150最高,分别为46.15%和12.98kg/kg;氮肥生理效率以处理W1200N150最大,为34.49 kg/kg。本试验条件下,以水氮处理W1500N150的土壤硝态氮残留量、表观损失量较低,夏玉米氮肥回收效率和农学效率较高。