本文介绍了广东省惠州市惠城区在开展农用地土壤污染状况详查工作的经验,包括组建技术队伍、野外采样、质量控制等方面,以期为全面提升广东省土壤污染防治能力提供经验支撑.

[目的]对比分析惠城区种植大户与普通农户主要作物施肥情况和存在问题,为判断区域农田施肥的合理性及调整肥料结构提供依据,探讨规模经营在化肥减量增效方面的积极作用.[方法]对惠城区91户农户肥料使用情况进行问卷调查和分析.[结果]调查区化肥使用量在合理范围内、有机肥施用量偏低.水稻平均产量不高,种植大户和普通农户水稻有机肥施用比例均较低,普通农户水稻化肥(N+P2O5+K2O)施用量为366.6 kg/hm2,N:P2O5:K2O=1:0.3:0.7,趋于合理;种植大户化肥(N+P2O5+K2O)施用量为421.1 kg/hm2,种植大户水稻化肥N:P2O5:K2O=1:0.5:0.7,存在高氮高磷问题.甜玉米平均产量较高,种植大户有机肥施用量高于普通农户,普通农户甜玉米化肥(N+P2O5+K2O)施用量为627.6 kg/hm2,N:P2O5:K2O=1:0.6:0.8,存在高磷问题;种植大户化肥(N+P2O5+K2O)施用量为508.1 kg/hm2,N:P2O5:K2O=1:0.5:0.5,存在高磷低钾问题.蔬菜有机肥施用量种植大户高于普通农户,但仍低于推荐施用量,普通农户蔬菜化肥(N+P2O5+K2O)施用量为685.4 kg/hm2,N:P2O5:K2O=1:0.7:0.7,存在高磷问题;种植大户化肥(N+P2O5+K2O)施用量为285.9 kg/hm2,N:P2O5:K2O=1:0.3:0.5,存在低钾问题.种植大户在甜玉米和蔬菜两种作物上化肥施用量分别比普通农户低19.0％ 和58.3％.[结论]种植大户等新型经营主体在增施有机肥、化肥减量等方面具有较大潜力,建议可以有针对性地提出化肥减量增效调控对策.

在惠城区中等肥力地块进行甜玉米“3414”试验,结果表明:施肥增产效应显著,且可获得较高的经济效益,其中产量、产值、增收产值最高的是N3P2K2处理,收益最高的是N2P1K2处理;N、P、K对玉米产量贡献大小顺序为N＞K＞P,增施氮肥有一定增产效果,其次是钾肥,磷肥增产效果最小.三元二次方程回归与显著性分析结果表明:氮、磷、钾肥施用量与产量的回归关系显著,氮、磷、钾的最大施肥量分别为:N最大为38.01 kg/667m2,P最大为24.65 kg/667m2,K最大为38.83 kg/667m2,相应产量为1 023.8 kg/667m2;考虑施肥成本和玉米价格的边际效应,氮、磷、钾最佳施肥量分别为:N最佳为22.61 kg/667m2,P最佳为13.05 kg/667m2,K最佳为19.89 kg/667m2,相应产量为955.70 kg/667m2.

为解决生产上存在的盲目和过度施肥现象，提高肥料利用率，设计了惠城区花生测土配方施肥试验。结果表明：试验各处理对花生的农艺性状有一定影响，对产量的影响尤为明显。在固定施P2O53.0 kg/667m2下，建立花生产量与N、K2O 2种肥料之间的回归方程，并得出花生最佳施肥量为：N 6.5 kg/667m2、K2O 9.7 kg/667m2。

The present experiment was conducted to analyze the effect of no-tillage and straw covering for sweet potato on the soil total organic carbon content,active organic carbon,carbon pool and the quantity of microorganism using conventional cultivation as the control.The results indicated that the no-tillage cultivation with straw covering enhanced the total organic carbon and active organic carbon contents and the carbon pool indices in 0-10cm depth of soil layer,while it had no significant effects on 10-20 cm depth of soil layer.It was found that the quantity of bacteria,fungi and actinomyces in 0-10 and 10-20 cm depth of soil layer was higher than that of conventional cultivation,which demonstrated that no-tillage with straw covering could increase the quantity of soil microorganism.Therefore,applying no-tillage with straw covering for a long time would be beneficial for enhancing the soil fertility,and improves environment for soil microorganisms.

以"桂薯131"为试验材料,进行红薯3种不同栽培模式比较试验,探讨不同耕作方式对红薯生理特性的影响.结果表明,在整个生育期,免耕稻草覆盖栽培红薯的根系活力均比传统栽培的高,在生长中后期,免耕稻草覆盖栽培的红薯叶片叶绿素含量、游离脯氨酸含量、过氧化氢酶活性、超氧化物歧化酶活性均显著高于传统栽培;两种免耕栽培处理方式比较,以先在畦面覆盖3cm厚稻草,摆放薯苗,然后覆盖8cm,厚稻草处理红薯的各项生理指标最高.

In the experiment,Guishu131 of sweet potato was used and three different cultivations were designed to study effects of no-tillage with straw coverage on agronomic characters,physiological characters,yield and quality of the sweet potato and soil fertility.The results showed: compared with traditional cultivation,both cultivations of no-tillage with straw coverage were higher in the agronomic characters,such as the length of vine,the numbers of leaves on stems and the numbers of the branches,physiological characters,such as the root activity,chlorophyll content,SOD activity,CAT activity,and the soil nutrients.The yield and rate of large and medium sweet potato of no-tillage with straw coverage was highest,and the content of reducing sugar and soluble sugar was higher than that of the traditional cultivation to some extent.

The taxonomic,morphological and physico-chemical characteristics of purple soils profile of Guangxi have been studied using the theories,methods and standards of Chinese soil taxonomy combined with data obtained during second soil survey of Guangxi.The results showed that the formation of purple soil of Guangxi was the result of the effects of physical and chemical weathering and erosion on purple sandstones,conglomerates,mudstones and shale.The differentiation of purple soil profile was not significant and most of the purple soil had blocky structure with sandy loam texture.The contents of organic matters,total N and K in natural soil were found above average levels.However,the contents of organic matters,total N and available P in surface soil decreased significantly with great variability in pH ranging from 4.0-8.5.The purple soil of Guangxi could be classified into two soil orders(Cambosols and Primosols),two suborders(Udic Cambosols and Orthic Primosols),two soil groups(Purpli-Udic Cambosols and Purpli-Orthic Primosols) and nine subgroups(Trunic Pupli-Udic Cambosols,Agric Pupli-Udic Cambosols,Dystric Pupli-Orthic Primosols,etc.).

The present experiment was conducted using sweet potato with no-tillage and rice straw coverage in lateritic soil of paddy field to study the effects of different tillage conservation modes on carbon,nitrogen and nitrogen mineralizing bacteria in soil and their correlation.The results indicated that conserving tillage could increase the content of total organic carbon,active organic carbon,total nitrogen and alkali-hydrolyzable nitrogen in the soil layer of 0-10cm,while decreased the C / N ratio in soil.The quantity of ammonifying bacteria in different tillage conservation treatments increased twice compared to traditional tillage in both,0-10 as well as in 10-20cm soil layer.Further,the quantity of nitrifying bacteria in different tillage conservation treatment significantly differed from that of traditional tillage in 0-10cm soil layer,while no significant difference was observed in 10-20 cm soil layer.These results demonstrated that conserving tillage could increase the contents of organic carbon and nitrogen,and decrease the C / N ration in soil which is beneficial for the growth of nitrogen mineralizing bacteria and provide more available nitrogen for the crops.

The experiment was conducted to study the effects of no-tillage with coverage on carbon and nitrogen contents and nitrogen-mineralizing bacteria in soils cultivated with winter potato.The soils were treated with(1) traditional cultivation(CK);(2) no-tillage with rice straw-covering(8 cm);(3) no-tillage with rice straw(8 cm) and black film-covering.The results showed that the carbon and nitrogen contents and nitrogen-mineralizing bacteria in 0-10 cm depth of soil were significantly higher compared to those in 10-20 cm depth of soil in each treatment.The contents of total organic carbon,active organic carbon,total nitrogen and alkaline nitrogen and the amount of ammonifying-bacteria and nitrobacteria in 0-10 cm depth of soil,in treatments 2 and 3,were significantly higher compared to traditional cultivation treatment.The differences of contents of total organic carbon,active organic carbon and total nitrogen and amount of ammonifying-bacteria between the coverage treatments and CK were significant or highly significant in 0-10 depth of soil.However,no significant differences of the above indicators in 10-20 depth of soil were observed between coverage treatments and CK.The results revealed that the regulation of no-tillage with coverage might increase the contents of carbon and nitrogen and amount of nitrogen-mineralizing bacteria in surface soil,and is helpful for decomposition and mineralization of organic nitrogen in soils to provide sufficient available nitrogen for proper growth of the crop.Therefore,it was an effective cultivation techniques and suitable for extension and application in production.

The experiment was conducted with two treatments of conservation tillage of winter potato(Solanum tuberosum L.), no-tillage with mulch of 8 cm-thick rice straw and no-tillage with mulch of 8 cm-thick rice straw covered with black plastic, to study the effect of the conservation tillage on the soil nutrient and the organic carbon pool. The results indicated that: the conservation tillage could increase the content of the soil nutrient, the content of nitrogen in the soil increased 0.81%～7.24%, the content of phosphorus increased 14.95%～19.21%, and the potassium increased 0.57%～15.40% compared with the traditional cultivation, and also the contents of total nitrogen, total phosphorus, total potassium had the significant difference with the conventional cultivation. The content of available phosphorus and available potassium was significant higher than that of the traditional cultivation; and the conservation tillage could increase the content of the total soil organic carbon and the soil active organic carbon, enhance the soil carbon pool management index in the soil of the depth of 0～10 cm, the soil carbon pool management index in the soil of 0～10 cm depth was 9.10% and 13.95% higher than the traditional cultivation’s; and the soil carbon pool management index in the soil of 10～20 cm depth was lower than the traditional cultivation’s. Thus conservation tillage had effects to improve soil’s quality. There was no significant different effect between the two conservation tillage.

<正>去年9月,"三鹿奶粉"事件不仅仅暴露出乳制品行业存在的生产和原料问题、企业和社会责任问题、行业监管问题,而最大的问题应是中国的食品安全以及农产品安全问题。一时间社会和媒体闹得纷纷扬扬令国人担忧,同时也引起了党中央和国务院的高度关注、高度重视。因为远比乳制品影响更为深远的就是中国食品和农产品的安全。而导致这些问题的根源和关键就在于引起超标毒物残留的化学农药和化学化肥。这不仅严重影响食品及农产品的质量和安全,还直接危害人民群众的身体健康,也影响了广大农民的增收。