Dynamics of zinc under long-term application of chemical fertilizers and amendments by maize–wheat cropping sequence in Typic Hapludalfs

This present investigation took place on a continuing long-term fertilizer experiment, initiated in 1972 at the experimental farm of the College of Agriculture CSK HPKV, Palampur, aimed at studying nutrient dynamics of micronutrients, especially Zn, after continuous use of chemical fertilizers and amendments over the previous 36 years in an acid Alfisol under a maize–wheat system. Treatments investigated were as follows: T₁: Control; 100% N; 100% NP; 100% NPK (optimal application - 120:26:33(maize)/25(wheat)); 100% NPK + FYM (10 t ha⁻¹ to the maize crop); T₆: 100% NPK + lime (900 kg ha⁻¹); T₇: 100% NPK + Zn (25 kg ha⁻¹ as ZnSO₄); T₈: 100% NPK + Hand weeding; T₉: 100% NPK (-S); T₁₀: 150% NPK (super-optimal application); and T₁₁: 50% NPK (sub-optimal application). Different forms of zinc in soil were determined through a sequential extraction method. Results revealed that previous applications of high-analysis fertilizers and amendments caused a marked depletion in the pools of Zn as compared to buffer plots. All pools of Zn as well as crop productivity and Zn uptake were noticeably greater in farmyard manure (FYM)-amended plots compared with plots not receiving fertilizer. The residual fraction was the dominant form but organically bound and exchangeable forms were found to play major role in nutrient supply, crop productivity and nutrient uptake. Correlation and regression analysis studies showed that organic forms constituted the most important pool contributing towards variation in yield and uptake by maize and wheat crops. Exchangeable and organically bound forms contributed significantly towards the availability of DTPA-extractable Zn in soil.     

长期平衡施肥对潮土微生物活性和玉米养分吸收的影响

利用中国科学院封丘农业生态实验站农田生态系统养分平衡长期定位试验地,研究氮磷钾平衡施肥(NPK)与缺素施肥(NK、PK、NP)对土壤微生物生物量、酶活性、呼吸强度以及玉米养分吸收的影响。结果发现,与不施肥对照(CK)相比,NPK处理玉米根系与茎叶生物量、籽粒产量以及植株氮磷钾吸收量均大幅提高,NP处理次之,PK与NK处理则无显著影响;同一处理玉米茎叶与根系养分含量接近,而籽粒的全氮和全磷含量较高、全钾含量偏低;与NPK处理相比,缺施氮、磷或钾肥均直接导致玉米植株相应养分的明显亏缺或其他养分的过量富集,但在根系、茎叶和籽粒部位的累积情况存在一定差异。与CK相比,所有施加磷肥的处理(NPK、NP、PK)土壤微生物生物量(碳、氮、磷)、脱氢酶、转化酶、脲酶与碱性磷酸酶活性以及土壤微生物代谢活性和土壤基础呼吸强度均显著升高(p<0.05),土壤微生物代谢熵则显著下降(p<0.05),而缺施磷肥的NK处理除显著提高脲酶活性外(p<0.05),对其他指标均无显著影响。结果表明,氮磷钾平衡施肥在促进土壤微生物繁育和保育微生物代谢活性以及促进作物生长和保证养分吸收等方面显得非常重要,而缺素施肥中以缺施磷肥的不利影响最为突出。     

长期不同施肥和土地利用方式对塿土耕层碳储量的影响

利用土20年长期肥料定位试验研究了不同土地利用方式和施肥对土壤有机碳和无机碳储量变化的影响。试验包括休闲（Fallow, FL）、 撂荒（Setaside, SL）、 不施肥（CK）、 单施氮（N）、 氮钾（NK）、 磷钾（PK）、 氮磷（NP）、 氮磷钾（NPK）、 氮磷钾配合秸秆还田（SNPK）、 氮磷钾配合低量有机肥（M1NPK）和氮磷钾配合高量有机肥（M2NPK）11个处理。结果表明,CK和 FL 处理等质量耕层土壤有机碳储量仍维持在试验前水平,NP和 SL 处理显著提高了耕层土壤有机碳储量,年均增加分别达到 347 kg/hm2 和518 kg/hm2, 此4个处理等质量耕层土壤无机碳储量均较试验开始前（Initial soil, IniS）显著下降,尤其是NP处理显著低于其它3个处理。与IniS和CK相比,除NK处理外的所有施肥处理均显著地提高了等质量耕层土壤有机碳储量,其大小顺序为 M2NPKM1NPKSNPKNPKNPPKN,最大年均增加量为M2NPK 944 kg/hm2,最小为N 127 kg/hm2。施肥处理除PK和M2NPK处理外,其它处理等质量耕层土壤无机碳储量均较试验前明显降低,可能是由于土壤酸化所致。PK和M2NPK处理无机碳储量能够维持不下降,表明土壤无机碳和有机碳在适合条件下可能有某种关系。试验结果还显示,长期试验20年除M1NPK和M2NPK处理外,其它处理耕层土壤容重均明显高于试验开始前,表明等质量土壤碳储量与等深度碳储量相比可以更好地反映土壤碳的变化。     

长期施钾和秸秆还田对河北潮土区作物产量和土壤钾素状况的影响

以河北冲积平原典型潮土区小麦-玉米轮作长期定位试验（19922009年）为基础,分析了长期施用钾肥和秸秆还田对作物产量、 土壤钾含量及钾素平衡的影响。研究结果表明,不同处理下小麦、 玉米17年平均产量均表现为NPKStNPKNPStNP,其中,小麦、 玉米NPKSt处理比NP处理分别增产9.37%和19.23%,NPK处理比NP处理分别增产6.32%和18.25%; NPSt处理比NP处理分别增产2.76%和9.60%; 长期定位施肥下,各处理耕层土壤（020 cm）各施钾肥的处理其速效钾、 缓效钾含量均与NP处理差异极显著,且表现为NPKStNPKNPStNP; 各处理下层土壤（2040 cm）的速效钾、 缓效钾含量差异均不显著,从钾素平衡看,NP处理钾素表观年盈亏量为-170.0 kg/hm2,土壤钾严重亏缺; NPSt处理实际平衡盈亏率-58.4%,表观年盈亏量为-150.6 kg/hm2; NPK处理钾素表观年盈亏量-3.1 kg/hm2,盈亏率-1.0%,基本接近平衡; NPKSt处理实际平衡盈亏率36.8%,表观年盈亏量为111.4 kg/hm2。试验结果说明,在潮土区,在施氮、 磷肥的基础上,配施钾肥或秸秆还田不仅能持续提高小麦、 玉米的高产、 稳产生产能力, 而且对保持农田土壤钾素平衡、 有效改善耕层土壤钾素状况、 提高土壤肥力有重要的作用。     

Effect of P‐solubilizing Azotobacter chroococcum on N,P, K uptake in P‐responsive wheat genotypes grown under greenhouse conditions

Natural and mutant strains of A. chroococcum were isolated from Indian soils. Their ability to dissolve phosphate and their phytohormone production were tested under in vitro conditions. In addition the effect of bacterial inoculation of Azotobacter on N, P, K uptake by three P responsive wheat genotypes (Triticum aestivum L.) under greenhouse conditions at five nutrient levels (Control, 90 kg N ha^—1, 90 kg N + 26 kg P ha^—1, 120 kg N ha^—1 and 120 kg N + 26 kg P ha^—1) was studied. In vitro phosphate solubilization and growth hormone production by mutant strains was more than by the soil isolates. Inoculation of wheat varieties with the soil isolates and mutant strains of A. chroococcum showed greater NPK uptakes as compared with parent soil isolates. Mutant strains M15 and M37 were proved to be the most effective for all three wheat varieties with regard to NPK uptake as well as root biomass production under greenhouse conditions.     

Optimum Nutrient Rate and Nutritional Constraints in Tuber Crops Growing in Ultisol of India with Special Emphasis on Tannia

Tuber crops are generally grown in marginal lands with low native soil fertility. In India, laterite soils (acidic Ultisols) are the major soils for tropical tuber crops and are poor in innate fertility. Among tropical tuber crops, some have adapted to poor soils, such as cassava, whereas others such as tannia (Xanthosoma sagittifolium L.) cannot establish well in these soils and may manifest nutritional disorders, which ultimately result in the complete devastation of the crop. Therefore, we investigated the effects from a preliminary rate trial (PRT) and nutrient-omission pot trial (NOPT) using maize as a test crop and a NOPT with tannia to determine the optimum nutrient rate and limiting nutrients, as well as nutritional problems affecting the growth and yield of tannia. Each experiment was laid out in a complete randomized design with three replications and was conducted for both garden and paddy soils. The PRT revealed that the optimum nutrient requirements for the soils were different, with garden soils requiring nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), zinc (Zn), and molybdenum (Mo) at 200, 60, 160, 70, 60, 50, 4, 8, and 0.8 kg ha^?1, respectively, and paddy soil requiring twice these rates. The NOPT indicated that in addition to N, P, K, B, and Mo in both garden and paddy soils, Ca and Zn in paddy soils and S in garden soils were the constraining nutrients. The NOPT carried out with tannia indicated that the main nutritional problem was subsoil acidity-induced multinutrient deficiencies involving K, Ca, and Mg.     

吉林春玉米氮磷钾养分需求与利用效率研究

【目的】 明确吉林春玉米的氮、磷、钾养分需求和利用效率,为区域春玉米的高效合理施肥提供技术参数。 【方法】 整理2005—2013年国家测土配方施肥项目在吉林省开展的680个 “3414”田间试验,选取N₀P₀K₀、N₀P₂K₂、N₂P₀K₂、N₂P₂K₂和N₂P₂K₀ 5个处理,研究氮、磷、钾肥对春玉米籽粒产量、植株养分吸收量的影响,明确产量、养分吸收量与土壤基础养分供应能力的关系,评估春玉米的氮、磷、钾养分需求量和利用效率。 【结果】 吉林春玉米在氮磷钾配施处理 (N₂P₂K₂) 获得最高的籽粒产量和植株养分吸收量,平均产量达9.6 t/hm2,玉米氮、磷、钾养分平均吸收量分别为N 190.8 kg/hm2、P₂O₅ 87.0 kg/hm2和K₂O 215.1 kg/hm2。与不施肥处理相比,氮磷钾配施处理平均增产42.5%,植株氮、磷、钾养分吸收量平均分别提高57.5%、64.2%和49.5%。在其他养分充分供应基础上,增施氮、磷、钾肥平均分别增加吸收N 57.2 kg/hm2 (42.9%)、P₂O₅ 19.2 kg/hm2 (28.4%) 和K₂O 32.1 kg/hm2 (17.5%)。以缺素处理植株养分吸收量表征土壤养分基础供应能力,发现氮磷钾配施处理玉米产量和养分吸收量均随土壤基础养分供应能力的提高而逐渐上升,变化趋势均符合显著的对数关系。经测算,吉林春玉米氮磷钾配施处理生产百公斤籽粒平均需吸收N 1.98 kg、P₂O₅ 0.90 kg和K₂O 2.24 kg,比例为1∶0.45∶1.13。减氮、减磷和减钾处理的百公斤籽粒氮、磷、钾素需求量平均分别为N 1.69 kg、P₂O₅ 0.79 kg和K₂O 2.11 kg,与氮磷钾配施处理相比均显著下降,而且试验点间变异也明显增大。目前,吉林春玉米生产中氮、磷、钾肥的平均养分回收利用效率分别为33.7%、27.5%和45.3%,而平均生理利用效率分别为28.8、52.8和28.3 kg/kg。 【结论】 吉林春玉米对肥料养分的依存度较高,合理施肥是保持高产高效的重要前提。      

Modeling the Response of Cassava to Fertilizers: A Site-Specific Nutrient Management Approach for Greater Tuberous Root Yield

Conventional fertilizer-management strategy results in decreased fertilizer-use efficiency and unbalanced nitrogen (N)–phosphorus (P)–potassium (K) applications. The quantitative evaluation of fertility of tropical soils (QUEFTS) model was used for determining region-specific balanced NPK uptake requirements and recommendations for a target yield of cassava. Minimum and maximum internal efficiencies of N, P, and K were estimated as 35 and 80 for N, 250 and 750 for P, and 32 and 102 for K (kg tuberous root per kg nutrient removed). Linear increases in tuberous root yield with N, P, and K uptakes of 17.6, 2.2, and 15.6 kg N, P, and K per 1000 kg tuberous root yield were observed. Relationships between soil supply and soil chemical properties and between fertilizer nutrient recovery efficiencies with their rates of application were developed for major cassava-production regions. Good agreement between measured and predicted yields was observed while calibrating the model, which shows that the model can be used for making site-specific NPK recommendations for cassava in major cassava production regions of India.     

Response to micronutrient on carrots grown on a virgin sphagnum peat

Field studies were conducted over a period of years on a virgin sphagnum peat bog in St. Charles, New Brunswick to determine the effect of trace elements on carrot (Daucus carota L.) root yield and nutrient concentration. Addition of the trace elements, boron (B), molybdenum (Mo), copper (Cu), and zinc (Zn), did not affect the marketable carrot root yields, although yields differed significantly from year to year. Addition of B at 10 kg/ha resulted in leaf tissue B concentrations as high as 75 mg/kg. Addition of foliar Mo at 0.14 kg/ha and soil Mo at 0.56 kg/ha raised the leaf tissue Mo concentrations to 3 to 4 mg/kg. Copper applications at 30 kg/ha raised the leaf tissue Cu concentration to 12 mg/kg. Zinc addition at 10 kg/ha did not increase the leaf Zn levels which ranged from 44 to 58 mg/kg. The leaf tissue B, Mo, Cu, and Zn levels as low as 29, 0.17, 4, and 44 mg/kg, respectively, were not related to deficiency of these elements. Such leaf tissue concentrations of B, Mo, and Cu are marginal for optimum crop production on this bog and should be monitored periodically to detect any significant trends through continuous use of this bog in crop production.     

等氮条件下长期有机无机配施对春玉米的氮素吸收利用和土壤无机氮的影响

【目的】研究等氮量投入条件下,长期使用不同有机物料替代无机肥的适宜比例对玉米氮养分累积、运移和氮肥利用效率和产量的影响,可以为吉林黑土区春玉米高效施肥,维持并提高土壤肥力提供理论依据。【方法】以国家(公主岭)黑土肥力与肥料效益长期定位试验为研究平台,玉米品种郑单958为供试作物,设5个不同处理,即:不施肥(CK)、氮肥(N)、氮磷钾化肥(NPK)、粪肥+NPK(MNPK)、秸秆还田+NPK(SNPK)。在玉米苗期、拔节期、大喇叭口期、抽丝期、灌浆期和成熟期采集地上部植株样品,分析玉米植株不同部位的氮含量和累积量以及运移比例,计算氮肥利用效率。【结果】在玉米各生育时期,MNPK处理氮素累积量均高于NPK和SNPK处理;拔节期至大喇叭口期氮素累积量为19.67~86.44 kg/hm2,其中MNPK氮素累积量达到86.44 kg/hm2,为氮素累积量增加最多、吸收速率最快的时期;在成熟期,MNPK、NPK、SNPK、N和CK处理植株氮素总累积量分别达到286.2、276.2、249.4、151.7和63.6 kg/hm2,SNPK处理氮素累积量略低于NPK处理,MNPK显著高于NPK和SNPK(P0.05)。MNPK、SNPK、NPK和N处理中,叶和茎鞘总氮素转移量分别为99.0、79.7、87.2和41.8 kg/hm2,总的转移氮素对籽粒的贡献率分别为51.0%、47.7%、47.2%和43.4%,以MNPK处理的总氮素转移量和转移氮素对籽粒贡献率最高,与其他处理差异显著。在各处理中,MNPK、NPK和SNPK三个处理的氮肥偏生产力(PFP)均大于60kg/kg,以MNPK最高,达到65.4 kg/kg。与化肥NPK处理比较,SNPK氮素偏生产力和收获指数差异不显著。MNPK处理土壤无机氮的含量在玉米整个生育期一直高于化肥NPK处理,并在玉米大喇叭口期达到最高,达到60.83 mg/kg,并与其他处理差异显著。【结论】长期有机无机配合施用,不仅能有效调节氮素积累和转运,还能提高氮肥利用效率。在适宜氮用量为165 kg/hm2时,以农家肥氮替代70%,或秸秆氮替代30%化肥氮素,既减少化肥氮投入,又增加了土壤供氮能力,因此,有机肥氮替代部分化肥氮是吉林省黑土区春玉米氮素管理的有效途径之一。     

长期施肥对红壤pH、作物产量及氮、磷、钾养分吸收的影响*

在湖南祁阳典型红壤上进行不同施肥长期定位试验18年,观测了土壤pH、作物产量和氮、磷、钾养分吸收量的变化。结果表明,长期施用化学氮肥（单施氮肥、氮磷配施和氮磷钾配施）红壤pH明显下降,其中以单施氮肥降幅最大,18年降低了1.5个单位; pH降低主要发生在施肥的前8～10年,当pH下降到4.5时,其下降速度趋于缓慢并相对稳定。施用有机肥（化学肥料配施有机肥和单施有机肥）,土壤pH保持稳定或较试验开始有所升高,以单施有机肥处理pH升幅最大,升高1.0个单位。不施肥和施用化学氮肥的作物产量随着施肥年限均显著降低,其中小麦产量平均每年下降11～104 kg/hm2,玉米产量平均每年下降 24～210 kg/hm2; 而施用有机肥的作物产量保持稳定或稳定增加,其中化学肥料配施有机肥的玉米产量平均每年增加 101 kg/hm2。施用化学氮肥处理（除氮磷钾配施处理的玉米外）作物产量和氮、磷、钾养分吸收量与土壤pH均存在极显著正相关。可见,pH降低是作物产量和氮、磷、钾养分吸收降低的主要原因之一; 而施用有机肥能改善红壤酸度,尤其是化学肥料配施有机肥能获得持续高产,是红壤区的最佳施肥模式。     

Enhancement of the rootability of a structurally fragile tropical soil using gypsum and leguminous residues to increase the yield of maize

In humid tropical areas, a combination of factors related to soil conditions for root development contribute to decreased nutrient use efficiency. Our aim was to evaluate the combined effects of the application of gypsum and mulch from leguminous trees on rootability of root zone soil, root growth, phosphorus recovery efficiency and maize yield in a sandy loam soil prone to hardsetting. The experiment involved a randomized block design with four replications and six treatments: no residue or gypsum (control, C); leguminous residues (L); leguminous residues and 6 t/ha of gypsum (LG6); urea and 6 t/ha of gypsum (UG6); leguminous residues, urea and 6 t/ha of gypsum (LUG6); and leguminous residues, urea and 12 t/ha of gypsum (LUG12). Application of gypsum plus leguminous residues enhanced soil rootability, when applied to a tropical Arenic Hapludult, through the combined effects of increased porosity and decreased penetration resistance. These improvements facilitated root growth in deeper soil layers and greater nutrient uptake. Application of leguminous residues increased the input and retention of calcium in deeper layers. The use of large amounts of gypsum with leguminous residue, despite a significant increase in phosphorus uptake, did not result in a proportional increase in maize yield. Given the small differences in calcium content between the 6 and 12 t/ha gypsum treatments, applying a low dose of gypsum combined with leguminous residue, rather than administering a single large gypsum dose, is recommended for tropical sandy loam soils with low cation retention capacities.     

Long‐term application of biowaste compost versus mineral fertilization: Effects on the nutrient and heavy metal contents of soil and plants

In recent years the use of biowaste compost (BC) as a soil amendment is of increasing interest. The aim of the experiment was to investigate the influence of different fertilization systems: biowaste compost, annual average of 32 Mg ha^—1 BC (fresh matter) and mineral fertilizer (83:52:95 kg ha^—1 NPK fertilizer) on the nutrient and heavy metal contents of soil and plants. Soil samples (1997) and harvest products (1996—1998) from a field trial (initiated 1992) were analyzed for K, Mg, P, Cu, Mn, Mo, Zn, Cd, Ni, and Pb. The five‐year fertilization with composted biowaste did not influence the total contents of Cd, Mn, Mo, and Ni in soil. The total soil contents of Zn and Pb were significantly higher in soils of the BC treatment than in the unfertilized control. Both fertilized plots tended to have higher Cu and Zn contents in harvest products than the unfertilized control. The mineral fertilization inhibited the Mo uptake by plants. In 1998 the mineral fertilization led to higher, and the biowaste compost application to lower, Cd contents in potato tubers as compared to the control.     

The Influence of Heavy Metals and Mineral Nutrient Supply on Bituminaria bituminosa

With a view to the selection of plants for the re-vegetation of contaminated, semi-arid land, two populations of the perennial species Bituminaria bituminosa (Fabaceae) from the south of Spain were studied: one (“LA”) from a non-contaminated soil and the other (“C2”) from a similar soil having elevated total levels of Pb and Zn (1,112 and 4,249 μg g^?1, respectively). For sand-cultured plants receiving nutrient solution, flow cytometry showed that heavy metals, at the concentrations measured in aqueous extracts from contaminated soils, had only slight genotoxic effects on root tip cell nuclei. Both populations were also grown in both soils, in two pot experiments. In the first, shoot biomass of LA and C2 in the contaminated soil was decreased to similar extents, with respect to the “clean” soil. Tissue heavy metal concentrations were unlikely to have been phytotoxic, except in the case of shoot Zn for population LA, but there were tissue deficiencies of P and K for populations LA and C2, respectively. In the second pot assay, the stimulation of growth by NPK fertiliser confirmed that even though this soil had high total heavy metal levels, nutrient availability was the principal factor limiting growth. The lesser transport of heavy metals (Cd, Mn and Zn) to the shoot by the population from the contaminated site is a factor that should be considered when selecting B. bituminosa lines for the phytostabilisation of such sites.     

土区长期施肥对小麦-玉米轮作体系钾素平衡与钾库容量的影响

本文研究了土区小麦-玉米轮作体系长期氮磷钾化肥不同配合施用方式及氮磷钾化肥与秸秆或有机肥配合施用对钾素平衡以及土壤钾库的影响。试验包括9个处理,分别为不施肥（CK）、单施氮（N）、氮钾（NK）、磷钾（PK）、氮磷（NP）、氮磷钾（NPK）、氮磷钾配合一季秸秆还田（SNPK）、氮磷钾配合低量有机肥（M1NPK）和高量有机肥（M2NPK）。结果表明,除NK、PK和M2NPK处理外,其它处理小麦和玉米钾的携出量均大于钾的投入量,导致土壤钾素处于亏缺状态,20年累计亏缺量为6174333 kg/hm2。与试验前相比,长期施肥种植没有显著影响土壤全钾含量; 长期施用钾肥显著提高土壤速效钾含量,但长期不施钾肥处理的土壤速效钾含量也未显著降低; 无论施钾与否土壤非交换性钾（Mactotal K）以及非交换性钾中更容易被HNO3溶解提取的钾（Step K）均明显低于试验前水平。表明土壤非交换性钾可以作为该土壤钾素消耗的指标。考虑到施钾肥的经济投入和现有资源高效利用（如秸秆、有机肥）,从长远的角度出发,维持土壤钾素肥力以及土地可持续生产力,土区小麦-玉米轮作体系采用秸秆全部还田或施有机肥是必要的。     

Alfalfa Responses to Combined Use of Lime and Limiting Nutrients on an Acidic Soil

An on-farm field experiment was conducted on an acidic soil to investigate the effects of combined use of lime and deficient nutrients on herbage yield of alfalfa (Medicago sativa L.). Omitting lime and limiting nutrients led to elevated concentrations of aluminium (Al), iron (Fe), and manganese (Mn) in alfalfa leaves and stems and caused severe reductions in herbage yield of alfalfa. Combined use of lime (2 t ha^?1) and nutrients [phosphorus (P): 20 kg ha^?1, sulfur (S): 20 kg ha^?1, zinc (Zn): 4 kg ha^?1, and boron (B): 2 kg ha^?1] had the maximum increase in groundcover, root biomass, nodulation, leaf retention, leaf-to-stem ratio, herbage yield, crude protein, and nutrient composition of alfalfa. These beneficial effects were due to raised soil pH; improved calcium (Ca), P, S, Zn, and B nutrition; and reduced Al, Mn, and Fe toxicity. Aluminium and all the nutrients except copper (Cu) were more concentrated in alfalfa leaves than stems.

Aluminum concentration was about three times greater in the lower leaves than in upper leaves. Lower leaves also had much greater concentrations of Ca, Mg, K, S, Fe, Mn, Cu, and B compared with upper leaves. In contrast, P and Zn concentrations were greater in the upper leaves than in lower leaves. Results suggest that the combined use of lime and all the limiting nutrients may realize potential beneficial effects of alfalfa on acidic soils where more than one essential nutrient is deficient. This may increase growth potential, nitrogen contributions, and groundcover by alfalfa and reduce soil erosion and runoff.     

等氮配施有机肥对喀斯特峰丛洼地农田作物产量与养分平衡的影响

基于自2006年在广西喀斯特峰丛洼地区开展的长期玉米/大豆套作定位施肥试验,选择2010—2014年监测数据,探讨等氮量投入条件下,不同比例有机肥替代无机氮肥对喀斯特峰丛洼地玉米/大豆套作系统作物产量及土壤养分的影响,为喀斯特峰丛洼地农田作物高效施肥及提高土壤肥力提供理论依据。试验选取4个处理:对照(不施肥,CK)、平衡施用化肥(NPK)、有机粪肥替代30%化肥氮(C7M3,按氮素计算,不足30%的PK用无机肥补充,肥料总量与NPK处理相同,有机粪肥为牛粪,下同)、有机粪肥替代60%化肥氮(C4M6,按氮素计算,不足60%的PK用无机肥补充),每个处理4次重复。于2010年、2012年、2014年大豆收获后采集土壤样品,测定土壤养分状况。结果表明:1)施肥处理土壤有机质、全氮、速效磷及速效钾含量均高于CK处理,其中C4M6处理有机质含量显著高于NPK处理(P0.05),全氮、速效磷和速效钾含量随着有机粪肥施用量的增加而增加。2)长期不同施肥处理玉米和大豆产量分别是不施肥处理的4.15~4.36倍、2.47~2.58倍。不同施肥处理的增产效果为C4M6NPKC7M3,但施肥处理间差异不显著(P0.05)。3)长期不施肥CK处理玉米产量随着试验年限推移呈下降趋势,降幅为5.45 g·m~(-2)·a~(-1),大豆产量却表现出增加趋势,增幅为1.50 g·m~(-2)·a~(-1)。长期施肥处理中,玉米和大豆产量总体呈增加趋势。4)施肥处理中,玉米季表现为钾素亏缺(NPK处理除外),大豆季表现为氮素亏缺。综合两季作物,只有C4M6钾素表现亏缺,亏缺量为7.9 kg·hm~(-2)。磷素在各施肥处理中盈余量较大,分别为81.2 kg·hm~(-2)(NPK)、83.4 kg·hm~(-2)(C7M3)和74.8 kg·hm~(-2)(C4M6)。综上,在喀斯特峰丛洼地玉米/大豆套作制度下,基于作物产量及土壤养分表观平衡特征提出有机粪肥可以代替部分化肥施用,在玉米季适当"减氮、稳磷和增钾",大豆季"稳氮、减磷和减钾"的施肥措施。     

Use of velvet bean to improve soil fertility and weed control in corn production in northern belize

Abstract

The objective of this research was to mesasure the effect of intercropping corn (Zea mays L.) with velvet bean (Mucuna pruriens) oil corn yields, soil fertility, and weed control in northern Belize. Two soils were used which are widespread in the area. These soils are high in clay (simectitc) and are well supplied with bases. One soil, the Louisville, has a black surface horizon overlying light gray to white calcareous weathered coral. The other soil was Xaibe which consists of a reddish‐brown clay over hard limestone “cap rock”; at 30–40 cm. Both soils had a relatively high organic carbon (C) and total nitrogen (N) content. We classified the Louisville as Calciustert and the Xaibe as a Ustropept. The treatments used (carried out annually in 1990, 1991, and 1992) were residue burn (B), bum plus fertilizer (BF), a velvet bean intercrop (G), and a velvet bean intercrop plus fertilizer (GF). Velvet bean intercropping did not have a positive effect on corn yields on these soils. For adequate yields to be maintained, it appears that fertilization with N, phosphorus (P), potassium (K) and certain micronutrients are required. We did obtain some indication that velvet bean intercropping will reduce weed population, including a serious infestation of cogongrass (Jmperata cylindrica). Velvet bean did not maintain the soil N content Corn yields decreased on the Louisville soil at San Victor from a range of 2,804 kg/ha to 3,181 kg/ha in 1990 to 1,783 kg/ha to 2,065 kg/ha in 1992. There were no significant treatment effects in any year. With the Xaibe soil, no yields were obtained in 1990 because of weed competition. In 1991, yields ranged from 555 kg/ha to 1,146 kg/ha (no significant treatment effects). In 1992, the fertilized plots, BF and GF, had corn yields of 1,391 kg/ha and 1,592 kg/ha, respectively. The unfertilized plots, B and G, had corn yields of 751 kg/ha and 699 kg/ha, respectively. We did obtain sufficient information valuable for persons making fertilizer recommendations on similar types of soil. The Mehlich 3 and the ammonium bicarbonate‐DTPA extractant (the latter extractant similar to that used in Belize) did not give good correlations between P and K leaf levels and corn yields. Where soil test P and K were often adequate, corn ear leaf levels were deficient (and presumably yields were reduced because of this metabolic deficiency). We concluded from both soil tests and leaf analyses that the micronutrients copper (Cu), manganese (Mn), and molybdenum (Mo) are seldom, if ever, limiting plant growth and grain yield, although there appears to be seasonal differences. With both soils, soil tests were not good indicators of zinc (Zn) concentrations in the leaf. In 1992, soil tests indicated adequacy of this element, although leaf Zn was deficient in all plots on the Louisville soil in 1990, most plots in 1992, and several plots on the Xaibe soil in both years.     

Liming and sulfur amendments improve growth and yields of maize in Rubona Ultisol and Nyamifumba Oxisol

Aluminum toxicity is a major limitation to crop production on highly weathered and leached soils in Rwanda. Moreover, sulfur though widely deficient in Rwanda acidic soils has received little attention by soil fertility researchers. A field experiment on maize response and soil nutrients status to liming materials of travertines at 3.4 t ha^?1, ash wood 1.2 t ha^?1 of CaO equivalent and sulfur at 10 kg ha^?1 combined with NPK at 80, 60, and 45 kg ha^?1 respectively was conducted in Rubona Ultisol and Nyamifumba Oxisol. Results revealed that travertine and wood ash increased the soil pH from 4.7 to 5.8 or higher and decreased exchangeable Al³⁺ and H⁺ to near 0 cmolc kg^?1. Soil nutrients generally increased to high or medium ranges for crop production. Leaf dry biomass, plant height and maize grain yields were significantly higher in Rubona Ultisol than in Nyamifumba Oxisol. Plots that received wood ash, with NPKS or with NPK, generally had higher maize yields, followed by those which received travertines and NPKS or NPK which had maize growth response as compared to the control plots which received NPK only. Thereby, a combination of wood ash with NPKS or NPK, travertines with NPKS was found to neutralize soil aluminum toxicity, increase soil nutrients status to required levels for plant growth and increase maize yields significantly.     

Methods of adding micronutrients to a NPK formulation and maize development

Micronutrients are essential for plant development; however, micronutrient content in soil often is not sufficient. This study compared availability of boron (B), copper (Cu), manganese (Mn), and zinc (Zn) in the soil and their effect in developing maize plants, supplied from a physical mixture of nitrogen, phosphorus, and potassium (NPK) granules and micronutrients or from a granulated mixture of NPK coated with these micronutrients. The experiment was conducted in a greenhouse, with a Rhodic Acrustox soil and the formulation 4-30-10 [nitrogen-phosphorus pentoxide-potassium oxide (N-P₂O₅-K₂O)] with 0.1% B, 0.2% Cu, 0.2% Mn, and 0.3% Zn. A randomized block design with four replicates was used and the NPK formula doses used were 0, 150, 300, 600, 1200, and 2400 kg/ha. Coated NPK increased Zn levels in soil in 0.5 mg/dm³ in relation to its initial content, also causing an increase in plant dry matter. Compared with mixture, this increase was more than three times greater. Cu and Zn accumulation and Zn absorption were greater when their supply was made via coated granules. The larger dose of B via coated granules resulted in a greater B accumulation in comparison to the mixture. No differences were observed for the other variables when comparing both sources. Coating NPK granules with micronutrients was better than the mixture when comparing B, Cu, and Zn concentrations in the soil. Dry matter production of maize shoots and the accumulation of B, Mn, Cu, and Zn in it was greater when the fertilizer was coated with micronutrients.