坡地赤红壤不同利用模式对土壤磷和酶的影响

试验采用广东东莞花岗岩发育的坡地赤红壤为样品进行研究表明 :在坡地赤红壤的 4种利用模式中 ,旱地种植花生 ,荔枝可以有效地改善土壤的酸性 ,提高土壤肥力 ;提高土壤Al-P和Fe -P的含量 ,减少O -P的所占的比例 ,提高坡地赤红壤磷酸盐的有效性 ;增加土壤表层的脲酶和蛋白酶的活性 ,可能使土壤的磷酸酶的活性降低     

Particle arrangement and internal porosity of coarse fragments affect water retention in stony soils

Information about water retention in stony soils lags behind due to methodological difficulties. We applied a new strategy to measure the water retention in soils with coarse fragments (CFs) and to get insights into the effect of CFs porosity on water retention. Water retention at zero, 10, and 150 m suction, bulk density, and the mass fraction of six particle size classes were measured in undisturbed blocks from soils with variable CFs contents, originating from three parent materials. The results showed that some soils contain porous CFs (2–250 mm) with a water holding capacity as high as the fine fraction (<2 mm). The water held in the suction range of 1–150 m in a soil with porous CFs was twice as high as in soils with non-porous CFs. Multilinear regressions revealed that both the water retention capacity at 1 m suction and in the range 1–150 m were more dependent on bulk density than on the fraction of CFs and fine particles. In the soil with porous CFs, there was no correlation between their fraction and soil water retention. These results show that the bulk water retention capacity of soils with CFs is underestimated when not considering the internal porosity of the CFs. A better understanding of the effect of the porosity of CFs on bulk soil porosity and water retention is important to propose suitable pedotransfer functions and refine physically-based hydraulic functions for stony soils.     

A comparative study on chemical characteristics of tropical soils from volcanic material under forest and agriculture

Abstract

An investigation was conducted to compare differences in chemical characteristics of Costa Rica soils under continuous cultivation and under forest vegetation. Inceptisols from young volcanic material under forest, sugar cane, coffee and pasture, respectively, were sampled in the San Carlos region of Costa Rica, and analysed for pH, organic matter, N, Ca, Mg, K, Na, Al, Fe, Zn and Mn contents. Indications were obtained that continuous cropping for 1 to 22 years with sugar cane resulted in a decrease in Ca and Mg content and an increase in acid extractable Al concentrations, compared to amounts found in forest soils. In soils under coffee the only significant changes were a reduction in soil organic matter, N and Al contents. Exchangeable bases decreased slightly during the first two years, but in fields 15 years under coffee, the content of exchangeable bases was affected slightly, except for a relatively marked decrease in amounts of Mg. Conversion into pasture maintained soil fertility at a level comparable to that found in the forest soil ecosystem. It was concluded that differences in vegetational ecosystems caused soil chemical changes, but deforestation in the tropics did not necessarily result in rapid soil degradation processes. The magnitude of the data showed that the soil in the San Carlos region of Costa Rica had been cultivated for at least 10 to 20 years without producing evidence of excessive deterioration.     

赤红壤在不同农作制中养分平衡的研究

在广州的赤红壤上进行六种农作制的五年试验表明,所有衣作制的氮平衡均盈余,其中水稻连作的农作制氮盈余较少,而含豆科作物者尤其是牧草大绿豆混播及双季稻冬种绿肥盈余最多,后者年亩增加氮素约10kg;各农作制氮盈余的原因是具有较高的氮肥效率和土壤全氮量显著增加。磷平衡在所有农作制中皆为亏损;磷肥效率低,多数衣作制投入的磷约有1/3移至耕层以下。钾平衡在含水稻的衣作制中亏损艮大,旱作者接近平衡或盈余;钾亏损的原因是含水稻的农作制钾的淋失量大,平均达投入的44％:土壤经种植五年后钾含量一般只能维持原有水平。养分平衡状况表明,供试六种衣作制中,油一茨和牧草混豆科作物两个农作制最有利于养分平衡,亏损较少,其次是油—稻和稻—肥两个农作制亦较有利于养分平衡。试验还说明稻秆和豆科作物基秆回田是维持农作制中氮平衡、钾平衡的重要手段。     

长期不同施肥对赤红壤稻田区肥力的影响(英文)

阐明长期不同施肥红壤性稻田土壤肥力变化规律,探讨提高红壤性稻田土壤肥力的合理施肥模式。田间试验设CK(不施化肥)、N_1(N 60 kg/hm~2)、N_2(N 120 kg/hm~2)、N_1P_1(P_2O_530 kg/hm~2)、N_2P_1、N_2P_2(P_2O_560 kg/hm~2)、N_2P_2K_1(K_2O 45 kg/hm~2)和N_2P_2K_2(K_2O 90 kg/hm~2),各处理均施用腐熟牛粪作基肥,每季稻草按50%还田,连续10年不同施肥处理下红壤性稻田有机质、氮、磷和钾含量的变化规律。10年后各处理土壤有机质含量比试验前耕层土壤有机质含量平均增加2.5 g/kg,年均增加0.25 g/kg左右。各处理土壤全氮含量比试验前耕层土壤有机质含量平均增加0.35 g/kg,年均增加0.035g/kg,以N_2P_2K_1和N_2P_2K_2处理的土壤全氮增幅最大,平均每年增加0.052和0.048 g/kg。连续10年不施化学磷肥处理(CK和N_1、N_2),土壤全磷和有效磷含量基本上处于一种平稳状态。施用化学磷肥处理土壤全磷和有效磷含量呈逐年增加的趋势。N_1P_1和N_2P_1处理每年土壤全磷含量增加0.008 g/kg;N_2P_2、N_2P_2K_1和N_2P_2K_2处理土壤全磷含量年均增加0.012~0.013 g/kg。N_1P_1和N_2P_1处理每年土壤有效磷含量增加约0.8 mg/kg;N_2P_2、N_2P_2K_1和N_2P_2K_2处理土壤有效磷含量年均约增加1.4~1.6 mg/kg。连续10年不施化学钾肥处理(CK、N_1、N_2、N_1P_1、N_2P_1和N_2P_2),其土壤全钾含量基本上保持不变,而速效钾含量呈现出下降的趋势。施用化学钾肥处理中N_2P_2K_2土壤全钾、速效钾和缓效钾含量呈现逐年增加的趋势,其中全钾年均增加0.014g/kg。在施用有机肥基础上,增施氮磷钾化肥显著提高赤红壤区稻田土壤肥力水平,有机肥的施用是不断培肥土壤的有效措施之一。     

氮钾肥配施对赤红壤上甜玉米生长影响的研究

本文研究氮、钾肥配施对赤红壤上甜玉米生长的影响,于1986年秋作和1987年春作进行两次盆栽试验及植株和土壤的化学分析。结果表明:氮、钾肥配施可增加供试土壤有效氮和速效钾含量,可增加甜玉米穗叶(吐丝明)含N量和含K量,降低穗叶含P量、含Ca量和含mg量。不施钾肥处理的甜玉米穗叶含K量≤1.30％,吐丝前有明显的缺K症。施高量钾肥(0.33克KCl/公斤土)处理的穗叶含Mg量≤0.15％;吐丝后出现明显的缺Mg症;施K_1水平(0.17克KCl/公斤土)的钾肥较适宜。单施氮肥处理,甜玉米果穗和籽粒的产量随施氮量增加而显著降低。配施钾肥处理,甜玉米增产率随施氮量增加而增大。增施氮肥可明显增加籽粒粗蛋白质含量,降低水溶性糖含量。施钾肥与不施钾肥比可明显增加水溶性糖含量,增加粗蛋白质总量(克/盆),但降低租旦白质含量。在供试赤红壤盆栽甜玉米条件下,氮钾肥配施以N_2K_1处理为宜     

赤红壤水问题及其管理——以闽南漳浦县为例

本文叙述了闽南低丘台地上赤红壤水问题及其有效管理。指出了该区年降雨量虽然丰沛,但仍小于年蒸发量,季节性干旱和土壤高温非常严重,成为影响该区农业生产的主要障碍。而赤红壤的总库容、贮水库容和有效水库容都较小,进一步促进了旱情的发展,在气候、土壤、植被、水文、地形等因素综合作用下,赤红壤旱地水分问题显得特别突出,其上作物易遭受干旱的胁迫。完善灌溉设施,有计划发展喷灌、滴灌以及进行地表覆盖,能有效提高水资源的利用率。     

硅磷优化施肥模式对广西赤红壤甘蔗产量和品质的影响

[目的]研究硅磷优化施肥模式对广西赤红壤甘蔗产量和品质的影响,为建立广西甘蔗生态高值栽培技术提供科学依据。[方法]采取二次回归D一最优设计在广西隆安蔗地进行甘蔗田间试验,运用SAS统计分析软件对试验结果进行回归分析,建立多项式回归模型,并通过计算机程序对模型进行仿真寻优,寻求适合甘蔗营养模式的最佳硅磷配比。[结果]在该试验条件下,施磷及硅磷配施有利于甘蔗分蘖和生长,有较多的有效茎,并可获得较高的甘蔗产量和较优的品质。用SAS统计分析软件进行分析,得甘蔗产量（1,）、蔗糖产量（SY）与磷素（x,）、硅素（x：）之间的回归模型：Y=110096．92＋4356．91X1。＋2007．65X2-1592．35X1X2-5461．33X（^2,1）-7442．09X（^2,2）,R=0．914;SY=16471．85＋903．65X1,＋424．26X2-99．02X1X2。X2-1170．O8X（^2,1）-l 256．96X（^2,2）,R=0．930;该试验所建立的甘蔗产量和蔗糖产量回归数学模型与当地实际情况拟合较好,具有较强的实用性,可用作当地甘蔗施肥决策和预报。采用计算机进行寻优,分别得到甘蔗产量和蔗糖产量最佳的营养模式,即当磷硅肥用量分别为281．3kg（P205）／hm^＋。和405．0kg（SiO2）／hm2。（P2O5：SiO2=1：1．44）时,得到最佳蔗茎产量和蔗糖产量,分别为109 405．6和16682．3kg／hm2。。[结论]适合于广西赤红壤区土壤条件的甘蔗硅磷最佳组合方案281．3kg（P205）／hm2。和405．0kg（SiO2：）／hm2。（P205：SiO2：=1：1．44）。