论南方红黄壤地区饲草开发利用的几种途径

本文在论述我国南方红黄壤地区的自然特征、社会经济、资源与环境现状的基础上，对如何开发利用该区饲草进行了探讨，指出保护和改善生态环境，积极实行林草结合、种养结合、粮草轮作和发展种草配套养鱼以及调制人工干草制品，是该区丘陵山地发展饲草的有效途径。     

秋马铃薯栽培技术

屏南县自然条件适合秋马铃薯种植,从地块选择、品种选择、整地施肥、催芽播种、田间管理、病虫害防治等方面总结了秋马铃薯高产栽培技术。     

Maize Yields as Affected by Short- and Long-Term Improved Fallows: A Comparative Analysis in the Asian Humid Tropics

Improved short‐ or long‐term fallows are considered suitable low external input technologies for maintaining productivity and sustainability of tropical smallholder upland cropping units, although comparisons on the benefits of this technology are not widely reported. A field study evaluated the impact of improved short (6 months) and long‐term fallow (18 months) using Crotalaria juncea and Tithonia diversifolia, in relation to a natural fallow of the same durations, on the productivity of maize (Zea mays), the most important upland cereal in tropical Asia, over a minor season. The use of improved fallows, especially Tithonia, increased maize yields over the Crotalaria or natural fallow. While the overall yields of maize after a long fallow were greater, the beneficial impact of the green manures was significantly higher in the short fallows. The causal factors for this trend, including biomass production of the improved fallows and possible impact on soils, along with the greater benefits of short‐term fallows for increasing maize yields in the tropics due to lower requirements of unproductive time are presented.     

46份国外腰果种质经济性状分析

连续2年在海南省乐东县冲坡镇测定46份国外腰果种质植株的坚果产量、坚果重量、坚果大小、坚果出仁、尧果仁重量、果仁大小尧果仁质量等级等，并进行综合比较。结果表明，30份种质的经济性状较优异，可进一步开展种质比较试验，筛选出高产、稳产、优质的腰果新品系。     

重庆地区地栽栽培管理技术探究

近年来,柳荫镇依靠不断的探索和实践,逐步形成结构良好、增产丰收的农业新局面,尤其桑树园的发展,为其他农业地区提供了宝贵的经验。以柳荫镇桑苗的栽培管理技术为例,着重介绍了三种桑苗栽植繁育技术,对重庆地区桑树栽培实践具有重要的指导意义。     

水稻育秧返栽田与移栽大田稻水象甲幼虫的发生数量

为了探明水稻育秧返栽田与移栽大田稻水象甲幼虫数量的差异,为稻水象甲的防控提供依据,对洗秧前后、育秧返栽田与移栽大田的稻水象甲幼虫数量进行调查,并进行了稻水象甲幼虫在秧苗上的回接试验。结果表明:洗秧能洗掉稻水象甲幼虫,而洗掉于秧田的幼虫有42.00%～90.00%的能转移到返栽的水稻根上危害;水稻秧田期为稻水象甲的主要防治时期,育秧返栽田为重要防治田块。     

施肥对马尾松人工幼林生长的影响

为了探明施肥对马尾松人工林生长的影响,在桂西北干热河谷地区选择马尾松人工幼林建立固定样地,采用生物有机无机复混肥不同肥施量进行连续5年4个处理(即A 1.0 kg/株、B1.5 kg/株、C2.0 kg/株,以及CK不施肥)的肥效试验。当林分生长至9年生时,其生长量显示如下规律:(1)胸径生长量为C(11.40 cm)>B(11.10 cm)>A(10.87 cm)>CK(10.80 cm);(2)树高生长量为C(9.87 m)>B(9.43 m)>A(9.23 m)>CK(9.20 m);(3)林分蓄积量为C(79.35 m3/hm2)>B(72.45 m3/hm2)>A(68.34 m3/hm2)>CK(67.33 m3/hm2)。从总体上看,马尾松人工幼林生长量显示出施肥比不施肥提高1.5%～17.9%,其中,施肥量2.0 kg/株处理对林木生长的效果显著。     

大棚和露地栽培条件下梨果实发育特性的差异

以‘翠冠’和‘黄冠’梨为试材,分析比较了大棚和露地栽培条件下梨果实生长发育特性的差异。结果表明:大棚栽培的‘翠冠’和‘黄冠’梨果实生长发育期分别比露地栽培的长5 d和13 d,果实可溶性固形物、可溶性糖和单果质量均高于露地栽培的,且成熟果实纵横径比露地果实的大,果实细胞大小与果实大小变化一致。大棚栽培条件下,‘翠冠’和‘黄冠’果实不同发育时期的可溶性总糖、果糖、葡萄糖和蔗糖含量均高于露地栽培的;果实总酚含量较低,仅为露地栽培的54.8%和66.4%,总抗氧化活性的变化与总酚含量一致。大棚栽培条件下‘翠冠’和‘黄冠’果实硬度分别比露地栽培的低14.9%和13.7%。而大棚栽培的‘翠冠’和‘黄冠’梨维生素C含量比露地栽培的低。表明大棚栽培条件下的梨果实品质优于露地栽培条件下的。     

浅析北京奥林匹克公园的植物造景艺术

北京奥林匹克公园是2008年北京奥运会留给我们的宝贵财富,是北京人民休闲娱乐的后花园。本文重点对奥林匹克公园龙形水系和休闲花园的植物造景艺术进行了详细分析,包括丰富的植物种类和特点突出的植物配置形式,以引为城市园林的典范。     

Plant availability and leaching of 15N-labelled mineral fertilizer residues retained in agricultural soil for 25 years: A lysimeter study

Background

A high use-efficiency of fertilizer N remains essential to sustain high crop productivity with low environmental impact. However, little is known on the long-term lability of mineral fertilizer N.

Aims

To quantify crop uptake and leaching of ¹⁵N-labelled mineral fertilizer that has been retained in an agricultural soil for 25–30 years in crops with variable growing season.

Methods

A field plot received ¹⁵N-labelled mineral fertilizers over a period of 5 years and was then kept under arable cropping for 12 years. After relocation to 16 lysimeters, the topsoil grew set-aside grassland for the next 13 years. Then crop uptakes and leaching losses of ¹⁵N remaining in soil was tested over a 2-year period by either converting set-aside grass to production grassland, or by replacing it with spring barley (+/− autumn cover crop) or vegetation-free fallow. All treatments received unlabelled mineral N fertilizers.

Results

Crop uptake and leaching of ¹⁵N were generally highest in the first test year after termination of the set-aside. The leaching of residual ¹⁵N in soil declined in the order: vegetation-free soil (4.7%), spring barley (1.9%), spring barley + cover crop (0.7%) and production grassland (0.2%). Corresponding losses for the second leaching period were 2.7%, 0.9%, 0.4% and 0.06%. There was a fixed relationship between leaching losses of ¹⁵N and total N.

Conclusions

After residing in soil for 25–30 years, the lability of labelled mineral N fertilizer residues appeared slightly higher than the lability of bulk soil N. Autumn vegetation was crucial for reducing leaching losses.