低丘红壤有机碳库的密度及变异

在中国科学院红壤生态实验站,采样分析了不同利用方式下土壤有机C 库的密度及其变异。结果表明,低丘红壤有机C 的密度0 ~ 20cm为(2.09 0.69) kg/m2,0 ~ 100 cm为(5.01 1.46) kg/m2; 全N密度0 ~ 20 cm为(0.20 0.07) kg/m2, 0 ~ 100 cm为(0.59 0.14) kg/m2。从裸地到稀疏荒草地,0 ~ 20 cm和0 ~ 100 cm土壤有机C 密度可以提高1.0 kg/m2和1.7 kg/m2;而从稀疏荒草地到人工林地或园地,0 ~ 20 cm和0 ~ 100 cm土壤有机C 密度可以提高0.7 kg/m2和0.9 kg/m2;稀疏荒草地如果开垦利用为水田,经长期培肥达到高度熟化,则0 ~ 20 cm和0 ~ 100 cm土壤有机C 密度可以提高2.3 kg/m2和4.4 kg/m2。即使不同类型的人工林地和园地之间,0 ~ 20 cm和0 ~ 100 cm土壤有机C 的密度差异也可达到1.0 kg/m2和3.5 kg/m2。不同地形部位之间0 ~ 20 cm和0 ~ 100 cm土壤有机C 密度差异达到1.3 kg/m2和2.9 kg/m2,全N密度差异达0.1 kg/m2和0.3 kg/m2;不同肥力水平之间0 ~ 20 cm和0 ~ 100 cm土壤有机C 密度差异达到1.5 ~ 2.2 kg/m2和2.8 ~ 4.1 kg/m2,全N密度差异达0.07 ~ 0.11 kg/m2和0.20 ~ 0.23 kg/m2; 强烈侵蚀可以降低0 ~ 20 cm和0 ~ 100 cm土壤有机C 密度1.4 kg/m2和2.2 kg/m2。因此,通过调整土地利用方式,可以提高土壤有机C 库密度,增     

侵蚀型红壤植被恢复后土壤养分含量与物理性质的变化

为了解侵蚀型红壤植被恢复后土壤养分含量与物理性质的变化状况,采集了植被恢复17年和9年的两个定位试验点土壤样品。分析结果表明：侵蚀型红壤植被恢复后土壤养分含量明显增加。恢复17年的木荷、杉木林0～0．2m土层土壤全氮和有机质含量分别比对照增加了3．92倍、2．96倍、5．80倍和3．52倍,土壤有效养分中土壤有效磷含量增加幅度最大。植被恢复后土壤物理性质得到极大改善．表现在土壤容量明显降低,土壤总孔度、通气孔度增加和大于1mm大团聚体与大于0．25mm水稳性团聚体总量的增加。总的来看,恢复17年的木荷和恢复9年的黑麦草两处理．土壤物理性质改善最为明显．此两处理0～0．2m表层土壤容量比对照区降低了27．9％和20．41％,大于0．25mm水稳性团聚体总量分别比对照区增加了31．09％和29．96％,土壤总孔度和通气孔度分别是对照区的1．34倍、1．25倍、2．59倍和2．14倍。     

高接在不同基砧的锦橙上的华红脐橙的栽培表现及矿质营养含量年变化

田间调查了高接在两种不同基砧的锦橙上的华红脐橙的栽培表现及矿质营养含量年变化差异。结果表明,在栽培效应上,红桔基砧树体生长较旺,投产晚,果实小,果实含酸量较高、糖酸比较低,出汁率和Vc含量较高;枳基砧则相反。在矿质元素含量年变化上,不同基砧树的叶片矿质元素含量年变化趋势除Mn、Zn外,其它元素含量年变化趋势差异明显;不同基砧根系的各种矿质元素含量年变化趋势基本相似;在不同基砧树之间,除根系Mg、Fe含量外,叶片和根系的各种矿质元素含量在年周期内的差异明显。     

中国东南部红壤地区不同植被对土壤侵蚀和土壤养分的影响

The effect of different vegetation systems including bamboo plantation (BP), forest ecosystem (CF), citrus orchard (Ctr) and farmland (FL) on erosion and nutrients of red soil were investigated in hilly region of southeastern China to find effective control measures for soil erosion. The results showed that all the vegetation systems could significantly reduce soil erosion and nutrient losses compared to bare land (Br). The ability of different vegetation systems to conserve soil and water was in the order of Ctr > BP > CF > FL > Br. Vegetation could also improve soil fertility. The soil organic matter, total N and total P contents were much higher in all the vegetation systems than in bare land, especially for the top soils. Vegetation systems improved soil physical properties remarkably. Compared to the bare land, soil organic matter, TP, TK and available K, especially soil microbial biomass C, N and P, increased under all the vegetation covers. However, they were still much lower than expected, thus these biological measurements are still needed to be carried out continuously.     

红壤坡地雨水产流及其土壤流失的垫面反应

通过4年(1998～2001年)径流场定位观测研究,探明了不同植被垫面雨水产流过程中系统水土流失有显著性差异。水流失量为农作区>常绿灌木区、针叶林区>常绿果园区>退化区、恢复区。坡地不同垫面间雨水地表径流的差异存在,为坡地雨水利用和利用坡地集雨支持农田灌溉提供了依据和可调控性。土壤流失量受人为干预、耕作强度的影响很大,坡地从自然保护到作物栽培,系统的土壤流失量提高20倍。茶果林地的土壤流失低于作物耕种的2～3倍,而高于自然利用和自然保护的6～12倍。养分流失在数量和质量上皆取决于垫面构成。提出了利用坡地集雨优势,构建与单元生态系统水循环平衡相适应的坡地农林复合生态系统,并通过水平衡生态建设来维系生态系统的水分平衡。     

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     

稻草覆盖对坡地红壤培肥及作物增产的效果

研究了坡地红壤连续5年采用稻草覆盖措施对土壤肥力和作物产量的影响。结果表明,“稻草+化肥氮磷”(“Straw+NP”)处理的土壤有机碳和全氮、磷分别比不施肥(CK)的提高42.9%和17.4%、44.2%,有机碳和全氮的增幅约是纯化肥(NPK)处理的2倍。与CK和NPK处理的相比,“Straw+NP”处理能明显提高微生物生物量碳、氮、磷和溶解性有机碳、氮以及Olsen-P含量,差异达到显著(P<0.05)或极显著(P<0.01)水平。在等养分施用量的条件下,“Straw+NP”处理能显著提高油菜和甘薯的产量。因此,稻草易地覆盖是一种有效培肥坡地红壤和增加作物产量的途径。     

Sustainable agriculture evaluation model for red soil hill region of southeast China

Agricultural sustainability for economic development is important and a complex issue throughout the world; however,it is difficult to synthetically evaluate its use in the policy making process. The objective of this study was to evaluate sustainable agriculture in the red soil hill region of Southeast China through a newly proposed method combining four separate sub-systems: regional population (P), resource (R), environmental (E), and socio-economic (S). This new index system was proposed to appraise synthetically the agricultural sustainability of the red soil hill region from 1988 to 1996 with a two-step method assessing: a) the agricultural sustainability in each province independently and b) the relative sustainability of each province to the whole region. The first step only provided a development trend for each province based on its original situation, while the second step provided additional information on the comparative status of each province in agricultural development to the region as a whole. Higher index scores were found for the economy and resource categories denoting improvement. However, lower scores in the environment category indicated the improvement was achieved at the cost of deteriorating ecological surroundings due to an increasing population that demanded more from the agro-ecosystem and put heavier pressures on it. Results also showed that water and soil losses in this region were the major obstacles encountered in sustainable agriculture development. The assessment results were verified when compared with results from another method. This suggested that the new assessment system was reliable and credible in evaluating agricultural sustainability on a regional scale.     

杨梅的需钾特性及施钾对杨梅的增产效应

钾对杨梅产量和品质的影响仅次于微量元素硼。杨梅对N：P2O5：K2O的需要比例分别为1：0．5：2．69。浙江省杨梅主产区土壤（0-20cm）的全钾和速效钾含量分别为1．81-2．41g／kg和83-121mg/kg。施钾能显著提高杨梅产量和改善果实品质。株产50kg果实的杨梅树以施用1．0～1．5kg氯化钾并配施50g硼砂的效果较好，杨梅进行叶面施钾时以喷施0．5％KCl或0．5％磷酸二氢钾的效果较佳。     

红壤区稀土矿开发导致河流泥沙淤积量的估算--以江西省信丰县崇墩沟小流域为例

不合理的人为活动是侵蚀产沙的主要原因之一。在江西省信丰县崇墩沟小流域内由于稀土矿产的无序开发,导致河流泥沙严重淤积。通过实测河流淤积泥沙断面,计算出在7 500 m长的河道共淤积泥沙30 193 t,考虑到输移比,整个流域内土壤流失量可达3 500 t/km2,平均侵蚀模数也高达1 150 t/(km2.a)以上,属于中等强度的土壤侵蚀。调查结果发现,河流中淤积的泥沙主要来源于稀土矿开发的尾矿流失;土壤流失量高到99 730 t/km2,年平均侵蚀模数为34 000 t/(km2.a)以上,属于极强度的水土流失。治理水土流失,须加强对稀土矿开发的管理,防止形成新的水土流失;将已废弃的稀土尾矿作为治理的重中之重,可有效地降低流域内土壤侵蚀的强度。