Isolation and Functional Characterization of Beneficial Bacteria Associated with Roots of Thysanolaena Maxima and Rhizospheric Soil Enzymatic Activities in Jhum Agriculture

The activity of amylase (AMY), arylsulphatase (ASA), β-glucosidase (GSA), dehydrogenase (DHA), acid-phosphomonoestarase (PHA) and protease (PRO) enzymes were analyzed in rhizospheric soils of broom grass, Thysanolaena maxima (TM) collected from fallow phases of 5 and 20 years Jhum cycles (F5 and F20, respectively) and their corresponding bulk soils. The activities of soil enzymes from rhizospheric soil of TMF5 were significantly higher relative to that of bulk soils and the rhizospheric soils from TMF20. The counts of rhizobacteria [0.74 ± 0.056 x 107 colony forming unit (cfu) g-1 soil] and root endophytic bacteria (0.083 ± 0.004 x 104 cfu g-1 roots) of TM from F20 fallow phase were higher compared to the counts of rhizobacteria and endophytic bacteria (0.27 ± 0.029 x 107cfu g-1 soil and 0.05 ± 0.008 x 104 cfu g-1 roots, respectively) of TM from F5 fallow phase. Altogether 63 isolates associated with TM were screened for multifaceted plant growth promoting (PGP) traits viz. production of pectinase and cellulase, IAA like substances, 1-aminocyclopropane-1-carboxylate deaminase (ACCD), N2-fixation, solubilisation of inorganic phosphorus (iP) from Ca3(PO4)2, AlPO4 and FePO4 and mineralization of organic phosphorus (Na-phytate). The PGP screening results indicated that the percent incidence of rhizobacteria and root endophytic bacteria for PGP traits was higher in F5 fallow phase as compared to F20 fallow phase. These results provided clear indication that TM plants play an important role in rejuvenating the biological activities (in terms of higher activities of enzymes in rhizospheric soils and greater population of beneficial rhizobacteria and root endophytes) in frequently burnt soils under shorter Jhum cycles.

Dicamba-resistant kochia (Bassia scoparia) in Kansas: characterization and management with fall- or spring-applied PRE herbicides

Dicamba-resistant (DR) kochia is an increasing concern for growers in the US Great Plains, including Kansas. Greenhouse and field experiments (Garden City and Tribune, KS, in the 2014 to 2015 growing season) were conducted to characterize the dicamba resistance levels in two recently evolved DR kochia accessions collected from fallow fields (wheat–sorghum–fallow rotation) near Hays, KS, and to determine the effectiveness of various PRE herbicide tank mixtures applied in fall or spring prior to the fallow year. Dicamba dose–response studies indicated that the KS-110 and KS-113 accessions had 5- to 8-fold resistance to dicamba, respectively, relative to a dicamba-susceptible (DS) accession. In separate field studies, atrazine-based PRE herbicide tank mixtures, dicamba + pendimethalin + sulfentrazone, and metribuzin + sulfentrazone when applied in the spring had excellent kochia control (85% to 95%) for 3 to 4 mo at the Garden City and Tribune sites. In contrast, kochia control with those PRE herbicide tank mixtures when applied in the fall did not exceed 79% at the later evaluation dates. In conclusion, the tested kochia accessions from western Kansas had evolved moderate to high levels of resistance to dicamba. Growers should utilize these effective PRE herbicide tank mixtures (multiple sites of action) in early spring to manage kochia seed bank during the summer fallow phase of this 3-yr crop rotation (wheat–corn/sorghum–fallow) in the Central Great Plains.

Evaluation of lablab and velvet bean fallows in a maize production system for improved livestock feed supply in semiarid tropical Kenya

The mixed crop–livestock farming systems of semiarid tropical Kenya are characterised by low livestock feed supply. The contribution of lablab and velvet bean to fodder production in a maize production system was investigated in the eastern region of Kenya. The experiment was run in three cycles, where each cycle consisted of a short legume fallow phase of ~6 months, followed by a maize-cropping phase. At the end of the fallow phase, the legume herbage was incorporated in soil at three levels; 0, 50 and 100% of total DM yield and maize planted. Maize yield from the legume fallow plots was compared with maize grown after natural fallow and maize top-dressed with 40 kg nitrogen/ha and nil nitrogen fertiliser. Overall, herbage DM yield was highest in velvet bean (3.9 t/ha) followed by lablab (3.4 t/ha) and lowest in natural fallow (2.2 t/ha). Mean crude protein from velvet bean was 13.5% of DM, which was significantly (P < 0.05) higher than that of lablab (8.4% of DM) and natural weedy fallow (3.5% of DM). Maize grain yield following lablab fallow was 38% (3569 kg/ha) and 27% (1810 kg/ha) in short rains (SR) 2002 and SR 2004, respectively, higher than maize succeeding natural fallow. However, maize planted after velvet bean fallow was 43% (3728 kg/ha) and 29.4% (1828 kg/ha) in SR 2002 and SR 2004, respectively, higher than in maize grown after natural fallow. Generally, the highest maize yield among the fallows was recorded in plots where legumes were incorporated in soil at 50% of total DM implying that the other 50% was available for livestock feed. Maize stovers DM yields were highest at the higher (100%) and middle (50%) level of legume incorporation, and yields were more than those from natural weedy fallow. Maize production under the legume fallow system was more profitable than from natural weedy fallows. It was concluded that if lablab and velvet bean are integrated in cropping systems as fallows, they can provide highly nutritious livestock feeds and improve maize yield and are recommended in the maize production systems within semiarid tropical Kenya.

Population Dynamics of Microarthropods (Oribatida and Collembola) in Rainfed Paddy Field Ecosystem in Pati, Central Java

A study on population dynamics of microarthropods (oribatids and collembolans) in rainfed paddy field ecosystem inPati, Central Java was undertaken with the aim to evaluate which group of soil microarthropods that dominated in each phase of rain fed paddy field. The soil fauna was collected using a soil corer of20 cm diameter to a depth of 0-15 cm, every 30 days.In the fallow, soil fauna was sampled from 4 randomized points per plot, meanwhile in the rice field phases (dry seeded rice and transplanted rice), it was sampled from 4 randomized points in the fields and in the bunds, respectively. per plot. Soil microarthropods in each season were then extracted in a Berlese funnel extractor.During the fallow phase, the dominant soil microarthropods were Oribatida of the Acari (1200 individual m,l) andsome groups of Collembola, namely Hypogastruridae (/200 individual m:2), Entomobryidae (500 individual m,l) andIsotomidae (620 individual m,2), meanwhile Sminthuridae of Collembola did not appear in this phase. In the rice phase,however, Sminthuridae of the Collembola occurred in high numbers, i.e., 860 individual m,2 (field) and 6/0 individual m,l(bund).Regarding the population dynamics of soil microarthropods in rainfed paddy field, we can assumed that oribatids and some groups of collembolans (Hypogastruridae, Entomobryidae and Isotomidae) play an important role in improving the nutrient availability during the fallow phase. meanwhile the Sminthuridae of collembolan seemed to play such role in the rice field phase. more than the other soil microarthropods.

The influence of a weedy habitat on the seed bank of an adjacent cultivated field

Seed traps positioned 1 to 100 m into a cultivated field were used to assess the seed rain from an adjacent weedy pasture. The cultivated field was in the fallow phase of a crop-fallow rotation. Two sets of traps were used: one set contained steampasteurized soil and the other contained untreated soil from the field. Traps were left in the field for 12 months and then transported to a greenhouse where they were kept for 12 additional months. Seed content was determined by field and greenhouse emergence of seedlings. The pasture was dominated by grasses, the most abundant being Poa pratensis, Stipa comata, Bromus inermis, and Agropyron repens. Seeds of pasture species were found in decreasing numbers in the fallow field, with few found more than 7 m from the fence line in traps of both sterilized and nonsterilized soil. The fallow field was dominated by species such as Setaria viridis, Thlaspi arvense, Descurainia sophia, and Salsola kali which were not found in abundance in the pasture. It was concluded that seed rain from the pasture had a significant influence on the germinable seed content of the soil of the cultivated field (at the edge only). The incursion of pasture species into cultivated land presumably has been restricted by cultural practices.

Effect of fallowing practices on the growth and yield of wheat in south-eastern Australia

The effects on crop establishment, crop development and the yield of wheat of two methods of fallow preparation, at each of three lengths of fallow were investigated over 5 years on red duplex and associated soils in north-central Victoria. The two methods of preparation were: scarifying, which involved the repeated use of a tined tillage implement; and herbicide application, which involved the repeated use of non-residual herbicides to control weeds during the fallow phase. The three lengths of fallow were winter, spring and autumn, which were approximately 10, 8 and 2 months respectively. Grain yield on the scarifier treatments was 0.26 t/ha greater (P<0.10) than on the herbicide treatments. Grain yield on winter fallow was 0.46 and 0.56 t/ha greater (Pt0.01) than on spring and autumn fallows, respectively. Crop yield was positively correlated (R2= 0.49) with soil nitrate determined at the time the crop was sown, but was independent of available soil water content determined at that time. Winter fallowing conserved 15 and 29 mm more water than did spring and autumn fallowing respectively, and mineralized 26 and 28 kg/ha more nitrogen than did spring and autumn fallows respectively. Crop establishment (No. of plants/m of row) on the herbicide treatment was 89% (P< 0.05) of that on the scarifier treatment, but this was not the reason for the reduced grain yield on the herbicide treatment. The lower yields were caused by depressed crop vigour (number of spikes/m of row) which in turn was largely a consequence of the inefficient uptake of nitrogen. The yield benefits of scarifying appear to reflect the importance of the initial two or three cultivations.