丰收时刻(组图)

夏天到了,田野里的麦子熟了,丰收的时刻来到了。阳光下的麦田是金色的海洋,风过时,会鼓荡起一排排麦浪,缓缓地起伏着,一波一波地涌向远方。一棵棵麦子被雨雪滋养过,被阳光照耀过,从麦秆到麦穗都是金灿灿的。它们肩并肩紧挨着,笔直地挺立着,仿佛大地的哨兵。布谷鸟在麦田上追逐嬉戏,在早春时,它们"布谷布谷"地催促农人播种。麦子黄时,又一声声欢叫着"黄了黄了",提醒农人们快来收割。吵吵闹闹的麻雀,让喷香的麦粒撑圆了肚子,惬意地停在稻草人的头顶或肩膀上。三五成群的蝴蝶、蜜蜂在尖尖的麦芒上跳舞。而稻花香里说丰年,听取蛙声一片的     

麦田O3干沉降过程及不同沉降通道分配的模拟

利用涡度相关系统对南京地区冬小麦田和裸土期O₃干沉降过程进行观测的基础上,引入Surfatm-O₃干沉降模型,对其叶片气孔阻力（R_s^leaf）、土壤阻力（R_soil）和表面阻力（R_cut）的公式进行参数化修订和验证,开展了冬小麦主要生育期的总O₃通量（F_O3）、干沉降速率（V_d）及其不同沉降通道分配的模拟,并间接分析了土壤排放的NO与O₃的化学反应对O₃干沉降过程的影响.结果表明：冬小麦田F_O3和V_d的实测值与模拟值趋势相似,平均实测和模拟V_d值分别为0.39和0.37cm/s,模拟值比实测值低估5.3%,其中每一个独立阻力公式的模拟效果均较好.平均非气孔沉降（表面沉降和土壤沉降）是O₃干沉降主要的沉降通道,占总O₃通量的68.8%,表面沉降占非气孔沉降的46.7%;平均绿叶和黄叶气孔沉降分别占总O₃通量的28.6%和2.6%.白天非气孔沉降比例减小至占总O₃通量的58.8%,绿叶和黄叶的气孔沉降比例比值增大,分别占总O₃通量的37.7%和3.5%.夜晚表面沉降和土壤沉降分别占总O₃通量的64.3%和35.7%.土壤排放的NO会与O₃产生化学反应,对O₃干沉降过程产生影响,需要在今后的O₃干沉降模型中考虑.     

甘肃东部旱作区不同气候类型麦田水分供需平衡研究

甘肃东部旱作地区干旱区年降水量小于300mm,半干旱区为300～450mm,半湿润区为450～600mm,湿润区大于600 mm4种气候类型1989～1992年14个测站0～2m深的土壤湿度实测资料,从降水土壤水作物系统观点出发,分析研究旱作小麦的实际耗水指标和耗水特点,探讨麦田水分供需平衡,为发展旱作区小麦高产稳产的栽培管理措施提供科 学依据。     

我是一个麦田守望者——一位在事故处理岗位上默默耕耘的普通民警自述

导语：主人公是一名从事高速公路交通管理工作十二年的老警察。在他身上没有卓著的业绩，也没有惊人的壮举，却有着对公安交管事业的热爱与追求。 他出生在医生家庭，儿时的理想是当医生，长达后却成为一名人民警察；但这丝毫不曾影响他在事故处理岗位上救死扶伤的信念：     

守望者萧玮

作为乐队麦田守望者的主唱,萧玮带领乐队屡屡走进人们的视野,成为中国摇滚音乐的一个标杆。而事实上,萧玮不仅仅是一名单纯的音乐人,更是一名坚定的环保主义者,对环保抱着极大的热情,并努力地付诸行动,雨林守望者、大象守望者是其继麦田守望者后一个又一个名副其实的绿色皇冠。     

近地层臭氧浓度升高对麦田土壤微生物群落功能多样性的影响

利用中国臭氧FACE(Free-air O3concentration enrichment,开放式空气臭氧浓度增高)试验平台,通过测定麦季土壤水溶性有机碳含量、土壤呼吸强度和BIOLOG指标,研究了近地层臭氧浓度升高50%条件下(~70 nmol mol-1),麦田土壤微生物功能多样性的响应.结果发现,臭氧浓度升高下麦田土壤水溶性有机碳含量提高,土壤微呼吸强度增加,平均吸光值显著高于对照(P<0.05).多样性指数结果显示,臭氧浓度升高对麦田土壤微生物丰富度和优势度指数没有显著影响,但是臭氧处理下均一度指数显著高于对照(P<0.05);主成分分析显示,相对于其它碳源,臭氧浓度升高对麦田土壤微生物的糖类物质利用能力的影响最大.研究揭示了1.5倍的近地层臭氧浓度增强了麦田土壤微生物碳源利用能力,特别是非优势微生物.     

Four years of free-air CO2 enrichment enhance soil C concentrations in a Chinese wheat field

Elevated atmospheric CO2 can influence soil C dynamics in agroecosystems. The e ects of free-air CO2 enrichment (FACE) and N fertilization on soil organic C (Corg), dissolved organic C (DOC), microbial biomass C (Cmic) and soil basal respiration (SBR) were investigated in a Chinese wheat field after expose to elevated CO2 for four full years. The results indicated that elevated CO2 has stimulative e ects on soil C concentrations regardless of N fertilization. Following the elevated CO2, the concentrations of Corg and SBR were increased at wheat jointing stage, and those of DOC and Cmic were enhanced obviously across the wheat jointing stage and the fallow period after wheat harvest. On the other hand, N fertilization did not significantly a ect the content of soil C. Significant correlations were found among DOC, Cmic, and SBR in this study.     

Soil temperature and moisture sensitivities of soil CO2 e ux before and after tillage in a wheat field of Loess Plateau, China

As a conventional farming practice, tillage has lasted for thousands of years in Loess Plateau, China. Although recent studies show that tillage is a prominent culprit to soil carbon loss in croplands, few studies have investigated the influences of tillage on the responses of soil CO2 e ux (SCE) to soil temperature and moisture. Using a multi-channel automated CO2 e ux chamber system, we measured SCE in situ continuously before and after the conventional tillage in a rain fed wheat field of Loess Plateau, China. The changes in soil temperature and moisture sensitivities of SCE, denoted by the Q10 value and linear regression slope respectively, were compared in the same range of soil temperature and moisture before and after the tillage. The results showed that, after the tillage, SCE increased by 1.2–2.2 times; the soil temperature sensitivity increased by 36.1%–37.5%; and the soil moisture sensitivity increased by 140%–166%. Thus, the tillage-induced increase in SCE might partially be attributed to the increases in temperature and moisture sensitivity of SCE.