Observed Climatic Variations in the Growing Season of Field Crops in Northeast China from 1992 to 2012

To determine the potential effects of climate change on crop phenological development and productivity, an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China from 1992 to 2012. A set of quality assurance procedures, including repeated record checks, agro-meteorological station selection, internal consistency checks, temporal outlier checks, spatial outlier checks, and interpolation of missing data, were designed and applied to the phenology datasets of spring maize and paddy rice. Our results indicated that almost all phenological dates of spring maize and paddy rice became increasingly delayed from 1992 to 2012, The duration of the growing season was prolonged, particularly for the grain-filling stage （GS3）. The prolonged growing season was beneficial to productivity. For spring maize, the average precipitation during GS3 decreased at a rate of 27.46 mm/decade, and the annual accumulated temperature over 10℃ increased at a rate of 31.07℃/ decade. Farmers initiatively adjusted crop cultivars and selected drought-resistant crops to cope with the challenges of drought.

A STUDY ON FIELD WATER CIRCULATION PATTERN IN THE DRYLAND OF NORTHERN CHINA

Based on the observed data of soil moisture from locating experiments from 1986 to 1990, the pattern of field water circulation in dryland of northern China, where the mean annual precipitation is 300 600 mm, is studied in this paper using the method of water balance. The results show that water satisfying ratio of spring seeding crops is 83.7 90.8 percent and that of winter wheat is about 70 percent in these areas; about 80 90 percent of water consumption of spring seeding crops and about 60 70 percent of water consumption of winter wheat comes from precipitation during the growing period, the rest comes from the soil water storage before the seeding period. But the available soil water is not used thoroughly, about 30 70 percent of available soil water remains unused when the crops are harvested. At the fallow period, the amount of soil water lost by evaporation is very important, which takes up 57 68 percent of precipitation in winter wheat field and 73 244 percent in field of spring seeding crops. Thus restraining soil evaporation, raising the storage ratio of natural precipitation and the soil water utilization efficiency of crops, strengthening the circulation ability of soil water by adopting efficient measures of agricultural techniques, are the main ways for exploiting and developing the potential productivity of natural precipitation in these areas.

Chemical Weeding in Dry Direct Seeding Fields of Single Cropping Middlelate Rice

Chemical weeding in dry direct seeding fields of single cropping middle-late rice was studied in Huida vegetable farm of Huizhou City in 2012. The main treatment was herbicide（ pretilachlor ＋ bensulfuron-methyl,Yangguo and butachlor）,and the sub-treatment was application method（ soil treatments,seedling treatment and integrated treatment）. The results showed that 80 g pretilachlor ＋ bensulfuron-methyl（ 36% pretilachlor ＋ 4% bensulfuron-methyl） diluted with 50 kg water could be sprayed or 200 g Yangguo（ 23. 9% butachlor ＋ 1. 1% bensulfuron-methyl） mixed with 15 kg sandy soil could be broadcasted per 667 m2 on the sowing day or the second day under moist condition of soil,which could effectively control weeds in dry direct seeding fields of single cropping middle-late rice.

Study on a new grain-cash cropping pattern in paddy field

We studied a new grain-cash cropping pattern composed of "barley/watermelon + waize-rice", comparing with "barley / watermelon-rice" (CKI), "watermelon-rice", (CK2). The experiment was conducted in CNRRI’s field for 3 yr, employing completely randomized design with three replications, and each plot occupied 207 m~2. The soil in the experiment field contained: N, 2.48 g. kg, quick effective P 4 mg. kg, and quick effective K 53 mg·kg. The varieties tested were Zhemai 2 (barley), Zhemi 1 (watermelon), Suyu 1 (maize), and Shanyou 63 (hybrid rice).

Multiple cropping and soil fertility in sustainable production of paddy fields

Multiple cropping has been popularized on morethan two thirds of the total area of paddy fields inSouth China.It demands more nutrients due tohigher cropping index.Therefore,how to keepmoderately higher yields of multiple crops and to

Multivariate Analysis, Description, and Ecological Interpretation of Weed Vegetation in the Summer Crop Fields of Anhui Province, China

Two surveys were conducted to investigate weed vegetation in a 153-hm^2 sampling area of summer crop fields from Anhui Province, China, through visual scoring of the level of weed infestation compared with summer crops on a seven-class scale. In total, 155 sampling sites were selected in the field based on crops, tillage, rotation systems, geographical regions, and soil types across the province. Data on weed communities and environmental factors were collected and analyzed through principal component analysis （PCA） and canonical correspondence analysis （CCA）, and the output was interpreted ecologically. Results showed that the main factors influencing the structure and distribution of weed communities in summer crop fields were the soil submersion period, latitude, and soil type and pH. The CCA indicated a significant relationship between weed dominance and soil submersion duration, latitude, and soil pH. From the result of the PCA and CCA ordination, the 155 sampling sites could be divided into three groups based on geographic and floristic composition, as well as weed abundance. The southern dry land group, which was characterized by a double-cropping system in the hilly regions of southern and central Anhui Province with a continuous summer crop and an autumn dry land crop, was dominated by Galium aparine Linn. var. tenerum （Gren. et Godr） Robb., Avenafatua L., and Veronica persica Poir. The northern dry land group, which had the same cropping system as the southern dry land group, was dominated by G. aparine var. tenerum, Galium tricorne Stokes, Descurainia sophia （L.） Schur., and Lithospermum arvense L. in the North Anhui Province, China. These two dry land groups could be combined into one large dry land group, in which the Galium weed vegetation type dominated. The third group was the paddy soil group, which was characterized by a continu- ous summer crop and double- or triple-cropping systems of rice, and prevailed in the south and central areas of Anhui Province; Alopecurus aequalis Sobol. was the dominant weed in this group. Other main weeds in this group included Malachium aquaticum （L.） Fries, Stellaria alsine Grimm, Alopecurusjaponicus Steud., and Lapsana apogonoides Maxim. Thus, the weed community distributions in this group were described as the Alopecurus weed vegetation type. The paddy soil group could be divided into two subgroups, one southern and one central paddy soil subgroup. A strategy for integrated weed management is suggested according to the weed distribution pattern. The present study serves as a good example of how a quantitative research method was used to associate a visual estimate of weed infestation with multivariate analyses, such as PCA and CCA, and how this method can be applied to the study of weed vegetation on arable land.

Greenness identification based on HSV decision tree

Greenness identification from crop images captured outdoors is the important step for crop growth monitoring.The commonly used methods for greenness identification are based on visible spectral-index,such as the excess green index,the excess green minus excess red index,the vegetative index,the color index of vegetation extraction,the combined index.All these visible spectral-index based methods are working on the assumption that plants display a clear high degree of greenness,and soil is the only background element.In fact,the brightness and contrast of an image coming from outdoor environments are seriously affected by the weather conditions and the capture time.The color of the plant varies from dark green to bright green.The back ground elements may contain crop straw,straw ash besides soil.These environmental factors always make the visible spectral-index based methods unable to work correctly.In this paper,an HSV decision tree based method for greenness identification from maize seedling images captured outdoors is proposed.Firstly,the image was converted from RGB color space to HSV color space to avoid influence of illumination.Secondly,most of the background pixels were removed according to their hue values compared with the ones of green plants.Thirdly,the pixels of wheat straws whose hue values were intersected with tender green leaves were eliminated subject to their hues,saturations and values.At last,thresholding was employed to get the green plants.The results indicate that the proposed method can recognize greenness pixels correctly from the crop images captured outdoors.

Examining the policy-practice gap-The issue of crop burning induced Particulate Matter pollution in Northwest India

The study examine the efficacy of government policy interventions initiated since 2014 to curb FCRB in NW Indian states and the related air pollution in Delhi-NCR during 2014-2019.The regression analysis suggests an increase in PM2.5 of~69μg/m3/1000 surge in fires.VIIRS retrieved data suggest an overall declining trend of~1606 and~4308 fire counts per year across NW states during October-November respectively.The monthly PM2.5 concentrations in New Delhi exhibits a decline of~2.18μg/m3 and~5.17μg/m3 per year over the same period.Despite an overall increase of~17.6%rice productivity,a noted decrease in fire activity over the period is an encouraging move,likely a result of some control imposed by authorities on FCRB.Owing to a significant~35.5%rise in wheat productivity,data records rising trend in wheat residue burning activities in April(~1298/year)and May(~2402/year)but do not trigger extreme pollution due to difference in intensity of fires across harvesting seasons and relatively weak northwesterly wind direction.Nevertheless,the overall high PM2.5 levels in October-November and April-May compared to NAAQS 24-hour average of 60μg/m3,disproves the overall efficacy of government policies to curb FCRB and related air pollution in IGP region.