Effect of some carbamate pesticides on nodulation,plant yield and nitrogen fixation byPisum sativum andVigna sinensis in the presence of their respective rhizobia

Summary Six carbamate pesticides namely 1-naphthol, sevin, dimetilan, trematan, NaDDC and dymid were studied to see their effect on nodulation and nitrogen fixation inPisum sativum andVigna sinensis. Low concentrations of the pesticides have little effect on nodulation and nitrogen fixation, whereas higher concentrations adversely effect these processes. The results also indicate that then sensitivity depends upon the species of the Rhizobium and also the type of the pesticide. Pesticides belonging to the carbamate group differ in their capacity to affect nodulation and nitroge fixation.     

Effect of soil moisture stress on yield,nodulation and nitrogenase activity ofMacroptilium atropurpureum cv. Siratro andDesmodium intortum cv. Greenleaf

Summary The effect of soil moisture stress on growth, nodulation and nitrogenase activity of two tropical forage legumes,Macroptilium atropurpureum cv. Siratro andDesmodium intortum cv. Greenleaf was studied in a pot experiment. After ten weeks growth, the highest moisture stress (20 per cent water holding capacity) significantly reduced only the top weight of both plants. Moisture stress progressively retarded top growth in the two legumes. Similar trends were also observed in defoliated plants. Moisture stress had little or no effect on the nodulation or nitrogenase activity of the plants.     

Effects of varying levels and frequencies of irrigation on growth,yield, nutrient uptake and water use efficiency of maize and cowpeas on a sandy loam ultisol

Summary A greenhouse study was carried out on an Nsukka sandy loam Ultisol having low soil moisture retention capacity to investigate the soil moisture regime and irrigation frequency required for optimum growth, yield, nutrient uptake and water use efficiency of maize (Zea mays L.) and cowpeas (Vigna unguiculata L. Walp). Four irrigation amounts (400 cm³, 300 cm³, 200 cm³ and 100 cm³ equivalent to 100, 75, 50 and 25% of field capacity, respectively) and four irrigation frequencies (daily, 2-day, 3-day and 4-day intervals) were tested in a factorial randomized design with three replications.Growth of maize was best when irrigation with water equivalent to 75% field capacity at daily interval but the optimum yields and nutrient uptake of both crops as well as cowpea nodulation were obtained when irrigating with water equivalent to 100% field capacity at daily or 2-day interval. The optimum water use efficiency was, however, achieved when irragating with amount equivalent to 100% field capacity at a 2-day interval. Irrigation with water equivalent to 50 or 25% field capacity at any interval resulted in various degrees of moisture stress which manifested in poor crop performance.     

Effect of two granular nematicides on growth and nodulation ofArachis hypogea L.

Summary The effect of two granular nematicidesviz. oxamyl and fenamiphos, on the nodulation and growth of Rhizobium inoculatedArachis hypogaea L. was studied in glasshouse and field trials. In the glasshouse trial at the suggested rates of application shoot fresh weight was significantly reduced by oxamyl whilst root fresh weight was similarly affected by fenamiphos. In the field trial vegetative growth and plant emergence were significantly reduced by both nematicides. Nodulation at the higher rates of application was increased by both oxamyl and fenamiphos whilst oxamyl caused a significant increase in pod number at the highest rate of application.     

Effect of soil sodicity on the growth,yield and chemical composition of groundnut (Arachis hypogaea Linn.)

Summary A replicated field experiment was conducted to study the effect of exchangeable sodium percentage (ESP) on the yield, chemical composition, protein and oil content and uptake of nutrients by groundnut (Arachis hypogaea Linn.) variety M-13. ESP over 15 delayed germination and emergence of flowers. There was continuous decrease in dry matter yield at 30 and 60 days of growth, grain and straw yield after harvest and protein, oil and kernel percent with increase in soil ESP. A 50 per cent reduction in groundnut yield was observed at an ESP of 20. Increasing soil ESP, increased Na and decreased K, Ca and N contents, but had no effect on the Mg, P, S, Fe, Mn, Zn and Cu contents of the plant. Sodium content of the plant increased, while potassium and nitrogen decreased with age of the plant. The uptake of all the nutrients decreased with increase in soil ESP. The results showed that groundnut is a relatively sensitive crop to soil sodicity.     

Effect of lime,phosphorus and mycorrhizal fungi on growth,nodulation and nitrogen fixation by white clover (Trifolium repens) grown in UK hill soils

Summary The responses of white clover (cv NZ Grasslands Huia grown in four UK hill soil types) to additions of lime and P, to inoculation with Rhizobium and mycorrhizal fungi, and to differences in soil water status were assessed in pot and field experiments. With a deep peat soil in pots, shoot production, nodulation and N fixation by clover were increased by 160, 130 and 85% respectively following inoculation with mycorrhiza, but in the field, despite a doubling of root infection, there was no response in growth. On a brown earth soil in the field inoculation with one endophyte (Glomus mosseae L1) out of four tested depressed production of white clover shoots by 42% but enhanced that of leeks (Allium porrum) by 50%; the others were without effect. With dry peaty podzol and brown earth soils in pots, clover shoot production was highest with added P when a water holding capacity of 80% was maintained, but roots from the latter had only 2.6 compared to 68 nodules per plant from the former. Further work is required to explain poor nodulation in the brown earth soils.     

Nutrient cycling in a tropical seasonal rain forest of Xishuangbanna, Southwest China. Part 1: tree species: nutrient distribution and uptake

Tropical rain forests are characterized by large numbers of the species with diverse growth habits. The objective of the present study was to determine the distribution of nutrient content in the major trees of the tropical rain forests in Xishuangbanna. This will improve the understanding of the nutrient losses from such sites that result from harvesting and flow of nutrients within the ecosystem and lead to the development of effective and rational forest management strategies. Based on the results in this study, the distribution of nutrients among biomass components of trees varied: The ordering of major elements concentrations was K>N>Mg>Ca>P in branch, stem and root tissues but was N>K>Mg>Ca>P in leaves. The maximum amount of all nutrients per ha occurred in the stems followed by branches, roots and leaves. Of the total uptake of 6167.7 kg ha⁻¹ of all nutrients, the contribution of various nutrients was found to be N (2010.6 t ha⁻¹), P (196.3 t ha⁻¹), K (2123.8 kg ha⁻¹), Ca (832 kg ha⁻¹) and Mg (1005 kg ha⁻¹). However, comparing the nutrient uptake of other tropical and sub tropical forests, the results indicated that rates for the Xishuangbanna forests were 20–35% lower than previously reported values.     

Effect of irrigation frequency and nitrogen on groundnut yield and nutrient uptake

Summary Field experiments were conducted during 1979 and 1980 summer seasons on sandy loam soils of low moisture retentive capacity to study the effect of high frequency irrigation at different levels of N on groundnut yield and nutrient uptake (NPK). Four irrigation frequencies (irrigation at 2, 4, 6 and 8 cm cumulative can evaporation, corresponding to irrigation once in 3, 5, 7 and 10 days respectively) and four levels of nitrogen (0, 20, 40 and 60 kg N/ha) were tested in a factorial randomized block design with three replications. Pod yield of groundnut was maximum (3,293 kg/ha) when irrigations were scheduled at 4 cm cumulative can evaporation (once in 5 days). Addition of N did not increase the pod yield. N and P uptake by the crop was maximum (180 kg N and 18 kg P/ha) with high frequency irrigation of scheduling irrigation at 4 cm cumulative can evaporation. Highest uptake of N (183 kg/ha) and P (19 kg/ha) was with a combination of 20 kg N/ha and high frequency irrigation (4 cm CCE). K uptake was low with low irrigation frequency, while it was highest (67 kg K/ha) at 20 kg N/ha.     

Effects of water regime on growth,yield, and nitrogen uptake of rice

Summary The effects of water regime on the performance of rice were investigated in a greenhouse experiment and two field experiments. The greenhouse experiment involved four water regimes (continuous flooding, and soil drying for 16 days — begun 2, 5, and 8 weeks after transplanting — followed by reflooding), four soils, and 0 and 100 mg N/kg. Soil drying raised the redox potentials of all soils beyond the aerobic threshold. Averaged for soils and N levels, yields from treatments in which soil drying was begun at 2 and 5 weeks after transplanting were lower than that from the continuously flooded treatment, but the simple effects of soil drying on yield and N uptake depended on the soil and the growth stage of the plant. None of the soil-drying treatments had adverse effects in the soil high in N but soil drying at 2 and 5 weeks after transplanting had adverse effects in the soil low in N. The field experiments tested the effects of three water regimes (continuous flooding, alternate drying and flooding every 2 weeks, and soil drying for 2 weeks at 6 weeks after transplanting following by reflooding), and 0, 50, 100, and 150 kg N/ha on a nearly neutral clay soil, during two seasons. None of the soil-drying treatments depressed growth, yield, or N uptake by rice at any level of N in either season. Nitrate was absent after drying, so denitrification was not possible on subsequent flooding. The adverse effects on yield of alternate flooding and drying, attributed to nitrification-denitrification, may be insignificant in wetland fields carrying an actively growing rice crop.     

A study of nodulation and nitrogen fixation of alder on the purplish soils in China

Summary The alder has a perennial nodule cluster. The nodule amount on the roots increases with tree age. The N₂-fixing activity of nodules decreases with nodule age. Purple coloured soils with various soil pHs and CaCO₃ contents are, in the main, the ones which influence nodulation and N₂-fixing. Higher N₂-fixing capacity existed in the neutral and low calcium soils. High calcium soils and acid soils can restrain nodulation and the N₂-fixing rate significantly. On the slope, where calcarous light loams are found, the annual nitrogen fixation capacity of alder and cypress mixed plantations, less than 10 years old, is 16 or 17 kg/ha yr, but in the valley, a pure alder plantation can reach 40 kg/ha yr.     

Biomass accumulations and nutrient uptake of plants cultivated on artificial floating beds in China's rural area

Focused on water pollution in China's rural area, taking Oenanthe javanica (Oj), Gypsophila sp. (Gy), Rohdea japonica (Rj), Dracaena sanderiana (Ds), Gardenia jasminoides Var. grandiflora (Gg), Gardenia jasminoides Var. prostrata (Gp), and Salix babylonica (Sb) as research objects, this paper investigated the growth characteristics and nutrient uptake of these seven species cultivated on artificial floating beds. The results indicated that after about 130 days’ acclimation, these seven species had different growth characteristics. The survival rates of each species were close to 100%. Dry matter biomass ranged from 33.7 to 307.1 g m⁻² in the following order: Sb > Gy > Oj > Ds > Gg > Gp > Rj. There were significant linear relationships between above-water and under-water biomass (R > 0.875); thus, the above-water biomass could best reflect the under-water biomass. N and P concentrations and distribution in the root, stem and leaf were quite different both within and between the species. N and P concentrations in plant body ranged from 15.31 to 23.15 g kg⁻¹ in the relationship Oj > Ds > Gy > Gp > Sb > Rj > Gg, and from 1.07 to 1.89 g kg⁻¹ in the relationship Rj > Gp > Oj > Gg > Gy > Sb > Ds, respectively. N and P accumulations ranged from 0.51 to 4.48 g m⁻² and from 0.062 to 0.331 g m⁻², respectively, in which plant nutrient uptake ability could be placed as follows: Sb > Gy > Oj > Ds > Gp/Gg > Rj. The outcomes also indicated that there were positive and significant linear relationships between N and P accumulations and plant biomass (R > 0.964), respectively; thus, plant harvest could be a means of taking N and P out of wastewater. Seven species, especially Sb, Gy, and Oj, had an ideal effect on TN and TP removal and could be widely utilized for the treatment of wastewater in rural areas.     

Effects of delayed soil and foliar N fertilization on yield and N2 fixation of soybean

Summary Field experiments were conducted to determine the effects of the amount, time and method of fertilizer N application on the efficiency of N uptake, N₂ fixatio and yield of soybean. Soil and foliar fertilizer N, applied during the pod-filling stage were absorbed by plants with equal and high efficiency, compared to an appreciably lower utilization efficiency for N applied before seedling emergence. These results reveal that the soybean roots were active in N uptake during these late stages of growth. Nitrogen fertilization during pod-filling resulted in significant yield increases over the control treatment which received an early application of 20 Kg N/ha. Seed yield increases were, however, more pronounced than total dry matter yield, and virtually all of the late-applied N was translocated into the pods. Nitrogen fixation in soybean was not influenced by the application of 40 kg N/ha to plants as soil or foliar N during the pod-filling stage. However, 80 kg N/ha supplied during pod-filling as 40 kg soil plus 40 kg foliar N/ha significantly reduced the amount of N₂ fixed. The results obtained in these studies suggest that inadequate N supply during pod-filling limited soybean yields, and that by the judicious application of fertilizer N during the late stages of growth, it was possible to enhance soybean yields without necessarily inhibiting N₂ fixation.     

Microbial biomass C,N and P in two arctic soils and responses to addition of NPK fertilizer and sugar: implications for plant nutrient uptake

The soil microbial carbon (C), nitrogen (N) and phosphorus (P) pools were quantified in the organic horizon of soils from an arctic/alpine low-altitude heath and a high-altitude fellfield by the fumigation-extraction method before and after factorial addition of sugar, NPK fertilizer and benomyl, a fungicide. In unamended soil, microbial C, N and P made up 3.3–3.6%, 6.1–7.3% and 34.7% of the total soil C, N and P content, respectively. The inorganic extractable N pool was below 0.1% and the inorganic extractable P content slightly less than 1% of the total soil pool sizes. Benomyl addition in spring and summer did not affect microbial C or nutrient content analysed in the autumn. Sugar amendments increased microbial C by 15 and 37% in the two soils, respectively, but did not affect the microbial nutrient content, whereas inorganic N and P either declined significantly or tended to decline. The increased microbial C indicates that the microbial biomass also increased but without a proportional enhancement of N and P uptake. NPK addition did not affect the amount of microbial C but almost doubled the microbial N pool and more than doubled the P pool. A separate study has shown that CO₂ evolution increased by more than 50% after sugar amendment and by about 30% after NPK and NK additions to one of the soils. Hence, the microbial biomass did not increase in response to NPK addition, but the microbes immobilized large amounts of the added nutrients and, judging by the increased CO₂ evolution, their activity increased. We conclude: (1) that microbial biomass production in these soils is stimulated by labile carbon and that the microbial activity is stimulated by both labile C and by nutrients (N); (2) that the microbial biomass is a strong sink for nutrients and that the microbial community probably can withdraw substantial amounts of nutrients from the inorganic, plant-available pool, at least periodically; (3) that temporary declines in microbial populations are likely to release a flush of inorganic nutrients to the soil, particularly P of which the microbial biomass contained more than one third of the total soil pool; and (4) that the mobilization-immobilization cycles of nutrients coupled to the population dynamics of soil organisms can be a significant regulating factor for the nutrient supply to the primary producers, which are usually strongly nutrient-limited in arctic ecosystems.     

Effect of plant nutrient supply on nodule effectiveness and rhizobium strain competition for nodulation ofLotus pedunculatus

Summary The effect of nutrient supply on nodule formation and competition between Rhizobium strains for nodulation ofLotus pedunculatus was studied. Limiting plant growth by decreasing the supply of nutrients in an otherwise nitrogen-free medium, increased the size but decreased the number and the nitrogenase activity of nodules formed by a fast-growing strain of Lotus Rhizobium (NZP2037). In contrast decreasing nutrient supply caused only a small decline in the size, number and nitrogenase activity of nodules formed by a slow-growing strain (CC814s). Providing small quantities of NH₄NO₃ (50 to 250 g N) to plants grown with a normal supply of other nutrients stimulated nodule development by both Rhizobium strains and increased the nitrogenase activity of the NZP2037 nodules. Differences in the level of effectiveness (nitrogen-fixing ability) of nodules formed by different Rhizobium strains on plants grown with a normal supply of nutrients were less apparent when the plants were grown with decreased nutrient supply or when the plants were supplied with low levels of inorganic N.Inter-strain competition for nodulation ofL. pedunculatus between the highly effective slow-growing strain CC814s and 7 other fast- and slow-growing strains, showed CC814s to form 42 to 100% of the nodules in all associations. The greater nodulating competitiveness of strain CC814s prevailed despite changes in the nutrient supply to the host plant. A tendency was observed for partially effective Lotus Rhizobium strains to become more competitive in nodule formation when plant growth was supplemented with low levels of inorganic nitrogen.     

Effect of farm yard manure and CaCO3 on the dry matter yield and nutrient uptake by oats (Avena sativa)

A pot culture experiment was conducted in loamy sand soil to study the effect of different levels of FYM and CaCO₃ on the dry matter yield and nutrients uptake by oats. Application of different levels of CaCO₃ (0, 2, 4 and 8%) and FYM (0, 0.5, 1,2%) resulted in significant increase in dry matter yield of oats. But, a little decrease in dry matter yield was obtained at 4% FYM. The interaction of FYM×CaCO₃ was also significant on dry matter yield of oats. There was a significant decrease in the concentration and uptake of P with increased levels of applied CaCO₃. But, application of FYM resulted in a significant increase in concentration and uptake of P. A significant increase in concentration and uptake of Ca was observed with the increasing levels of CaCO₃. The concentration of Ca decreased with the increased application of FYM in the presence as well as in the absence of added CaCO₃. However, at 0.5 and 1.0 percent FYM with 4 per cent CaCO₃ a little increase in Ca concentration was recorded. The Mg concentration in oat decreased significantly with the increasing levels of CaCO₃ and FYM. The effect of CaCO₃ levels was more pronounced in the absence as well as in the presence of FYM. The Mg uptake followed a different pattern. At 0 and 2% CaCO₃ and application of FYM @ 1 per cent the Mg uptake increased but then it decreased with increasing levels of FYM and CaCO₃ both alone as well as in the presence of each other. The concentration and uptake of Mn decreased with increasing levels of applied CaCO₃. However, in the absence of CaCO₃, the application of FYM increased the concentration and uptake of M_n in oats. In the presence of CaCO₃, Mn concentration decreased at all levels of FYM application but at 8 per cent CaCO₃ there was a slight increase in Mn concentration with 0.5, 2 and 4 percent FYM. Iron concentration and uptake was also affected adversely by increasing levels of CaCO₃ but FYM application removed the harmful effect of CaCO₃ to some extent.     

Effect of Rhizobium andAzospirillum lipoferum inoculation on the nodulation,yield and nitrogen uptake of peanut cultivars

Peanut (Arachis hypogaea Linn.) Cvs. Robut 33-1 and JL 24 were inoculated with Rhizobium strain NC 92 and a strain ofAzospirillum lipoferum singly and as mixed inoculum. Seed inoculation with these bacteria enhanced nodulation, N content and yield of these cultivars under field conditions. While a mix inoculation of these two diazotrophic cultures had an adverse effect on these parameters as compare to single inoculation.     

The effect of source,concentration and time of application of nitrogen on the growth,nodulation and nitrogen fixation ofLotus pedunculatus andTrifolium repens

Summary Studies under growth cabinet conditions investigated the effect of source and concentration of nitrogen and timing of nitrogen application on the growth and nitrogen fixation byLotus pedunculatus cv. Maku andTrifolium repens cv. S184. KNO₃, NaNO₃ and NH₄NO₃ were added at transplanting at the following rates: 3.33, 7.78 and 13.33 mg N/plant. KNO₃ was added at 3.33 and 7.78 mg N/plant at 0, 6, 12, 18, 24 or 30 days after transplanting.Lotus shoot weight increased with all increasing nitrogen sources but clover only responded to KNO₃ and NaNO₃. The root weight of both species increased with increasing KNO₃ and NH₄NO₃. The percentage increase in lotus and clover shoot growth was greater than that of root growth when KNO₃ was added within a week of transplanting. Increases in growth by both species resulted from added nitrogen except with lotus when NaNO₃ was applied where increased nitrogen fixation also contributed to increased growth.Weight and number of effective nodules on both species were increased with 3.33 mg N per plant as KNO₃ but nitrogen fixation was not affected. Addition of 13.33 mg N as NaNO₃ reduced weight and number of effective nodules in both species and also nitrogen fixation by lotus.KNO₃ increased growth and nodulation of both species when applied within one week after transplanting. Nodulated lotus plants responded to KNO₃ by increasing growth but not nodulation.KNO₃ appeared to affect infection and development of nodules on lotus and may affect the growth of existing nodules on clover.     

The effect of wood charcoal on the growth and nodulation of garden peas in pot culture

Summary In a factorial pot experiment on garden peas investigating the effect of growing medium, inoculation, nitrogen fertilisation and charcoal addition, shoot growth was significantly better in John Innes potting compost than in 50/50 peat/sand compost and when receiving nitrogen fertilisation but was depressed by the presence of wood charcoal.In the peat/sand medium, root systems were smaller but carried more and larger nodules. The number of nodules was increased by inoculation but the addition of carbon decreased root size, nodule number and nodule size.     

Prosopis glandulosa and the nitrogen balance of rangelands: extent and occurrence of nodulation

Summary We report the recovery of root nodules from P. glandulosa var. glandulosa in the eastern portion of its range, where the species reaches its greatest vegetational development. Single cores 4.7 cm in diameter and up to 250 cm deep yielded from 0 to over 250 nodules. Nodules were found at all depths below 10 cm, with the highest concentration often around 100 cm. Detailed studies of three trees revealed relatively small volume densities of about 0.02 nodules cm^–3, high surface area densities of 2–4 nodules cm^–2, and high nodule biomass of 8–23 g m^–2, when compared to cultivated legumes. Nodules are small, weakly attached to roots that are seldom over 0.5 mm in diameter, and not easily observed under field conditions. No nodules were recovered from cores from the more arid western portion of P.glandulosa's range, although seedlings nodulated readily in these soils in the glasshouse as well as in most unamended soils from throughout mesquite's geographical range. Local differences in nodulating potential of soils included a negative association with mesquite canopies and a positive association with depth. These results suggest a significant role for biological fixation in the nitrogen regime and vegetation dynamics of Prosopis-dominated ecosystems.