NPK Plots Research Articles

Effect of long-term different fertilization on bacterial community structures and diversity in citrus orchard soil of volcanic ash.

This study was conducted to assess bacterial species richness, diversity and community distribution according to different fertilization regimes for 16 years in citrus orchard soil of volcanic ash. Soil samples were collected and analyzed from Compost (cattle manure, 2,000 kg/10a), 1/2 NPK+compost (14-20-14+2,000 kg/10a), NPK+compost (28-40-28+2,000 kg/10a), NPK (28-40-28 kg/10a), 3 NPK (84-120-84 kg/10a), and Control (no fertilization) plot which have been managed in the same manners with compost and different amount of chemical fertilization. The range of pyrosequencing reads and OTUs were 4,687-7,330 and 1,790-3,695, respectively. Species richness estimates such as Ace, Chao1, and Shannon index were higher in 1/2 NPK+compost than other treatments, which were 15,202, 9,112, 7.7, respectively. Dominant bacterial groups at level of phylum were Proteobacteria, Acidobacteria, and Actinobacteria. Those were occupied at 70.9% in 1/2 NPK+compost. Dominant bacterial groups at level of genus were Pseudolabrys, Bradyrhizobium, and Acidobacteria. Those were distributed at 14.4% of a total of bacteria in Compost. Soil pH displayed significantly closely related to bacterial species richness estimates such as Ace, Chao1 (p<0.05) and Shannon index (p<0.01). However, it showed the negative correlation with exchangeable aluminum contents (p<0.05). In conclusion, diversity of bacterial community in citrus orchard soil was affected by fertilization management, soil pH changes and characteristics of volcanic ash.

Long-term fertilization modifies the structures of soil fulvic acids and their binding capability with Al.

The binding characteristics of organic ligands and minerals in fulvic acids (FAs) with Al are essential for understanding soil C sequestration, remain poorly understood. In this study, Fourier transform infrared (FTIR) spectroscopy combined with two-dimensional correlation spectroscopy (2DCOS) analysis was applied for the first time to explore the binding of Al with organic ligands and minerals in soil FAs. For these analyses, two contrasting treatments were selected from a long-term (i.e., 22-year) fertilization experiment: chemical (NPK) fertilization and swine manure (SM) fertilization. The results showed that the long-term application of organic and inorganic fertilizers to soils had little effect on the compositions of the fluorescent substances and organic ligands in the soil FAs. However, long-term SM fertilization increased the weathered Al and Si concentrations in the soil FAs compared with long-term chemical fertilization. Furthermore, organic ligands in the soil FAs were mainly bound with Al in the NPK treatment, whereas both organic ligands and minerals (Al-O-Si, Si-O) were bound with Al under the M fertilization conditions. Both transmission electron microscopy (TEM) images and X-ray diffraction spectra demonstrated that amorphous and short-range-ordered nanominerals were abundant in the soil FAs from the SM plot in contrast to the soil FAs from the NPK plot. This result illustrates the role nanominerals play in the preservation of soil FAs by during long-term organic fertilization. In summary, the combination of FTIR and 2D correlation spectroscopy is a promising approach for the characterization of the binding capability between soil FAs and Al, and a better understanding FA-Al binding capability will greatly contribute to global C cycling.

Screening and Evaluation Indicators for Low Potassium-Tolerant and Potassium Efficient Sweetpotato ( Ipomoea batatas L.) Varieties (Lines)

甘薯植株生长和块根形成与钾营养吸收利用密切相关。本研究以31份不同类型优质甘薯品种（系）为材料, 利用长期肥料定位试验田2个钾肥水平处理（氮磷处理与氮磷钾处理）, 探讨耐低钾与钾高效型甘薯材料的筛选及评价指标。结果表明, 该试验条件下, 不同甘薯品种（系）块根产量差异达显著水平（P〈0.05）; 供试材料的钾敏感指数变幅在0.40~0.98之间, 差异达显著水平（P〈0.05）, 经聚类分析, 可分为低敏感型、适度敏感型、敏感型和高度敏感型; 品种（系）两处理下钾累计量与钾浓度差异均达显著或极显著水平; 氮磷钾处理下, 块根钾利用效率与整株钾利用效率变幅分别为58.92~384.9 g g–1和42.03~ 165.52 g g–1, 品种（系）差异均达显著水平（P〈0.05）; 相关性分析显示, 不同甘薯材料间整株总钾累积量、钾浓度、产量性状指标、钾利用效率与钾敏感性间均有一定相关性。长期肥料定位试验田可用于不同钾营养效率甘薯品种（系）的筛选, 块根钾利用效率与钾敏感性可作为筛选耐低钾与钾高效利用型甘薯材料的2个主要指标。

Changes of Soil Physical Properties by Manured Sorghum Residues Incorporation

Although sorghum residue production was estimated to be <TEX>$8{\sim}10Mg\;ha^{-1}$</TEX>, most sorghum straw was used to be burnt or removed after harvest. This experiment was conducted to evaluate the effect of the incorporation of manured sorghum residues on soil physical properties from 2010 to 2012 in the converted paddy field. Five treatment with 3 replication consisted of control, inorganic fertilizer (NPK), manured residues, sorghum stover and sawdust manure. The incorporation level of organic source was <TEX>$10Mg\;ha^{-1}$</TEX> without inorganic fertilizer NPK. The investigated physical parameters were bulk density (BD), porosity, water stability aggregate (WSA), water infiltration rater (WIR), penetration resistance (PR) and soil water retention characteristics (WRC) with soil depth. The incorporation of manured sorghum residues improved WIR significantly over inorganic fertilizer (NPK), sorghum residues and sawdust manure. The BD by incorporating with manured residues on sorghum was reduced significantly with crop residue over plot of NPK and sawdust. Significant increase in WSA was observed with stubble incorporation alone or manured sorghum residues. Soil WRC were significantly enhanced with manured sorghum residue incorporated without NPK. The average PR at 0~15 cm was 0.54 MPa for manured sorghum residues. For sawdust manure plot it was 0.42 MPa, for Sawdust manure plot 0.39 MPa and for NPK plot 0.54 MPa.

Influence of farmyard manure application and mineral fertilization on yield sustainability, carbon sequestration potential and soil property of gardenpea–french bean cropping system in the Indian Himalayas

Sustainability of agricultural systems has become an important issue all over the world. Hence, sustainability and climate resilience of gardenpea–french bean cropping system was evaluated by yield trends, C sequestration and emission reduction and soil properties as affected by four application rates of farmyard manure (FYM) (5–20tha−1) vis-à-vis mineral fertilization, integrated nutrient management (INM) practices as 50% recommended NPK+FYM at 5tha−1 and un-amended control after six years of cropping in the Indian Himalayas. The highest sustainable yield index of 0.606 was achieved with the application of 20tFYMha−1 (FYM20). The carbon sequestration potential of FYM20 plots was about 459 and 193% more than NPK and INM plots, respectively. The same plots reduced 53 and 24% carbon equivalent emission with comparison to NPK and INM application, respectively. The soil cation exchange capacity (CEC) under FYM20 plots was 22 and 11% higher than NPK and INM plots. The soil cracking volume under FYM20 plots (57cm3m−2 area) was very less compared to NPK (324cm3m−2 area) and INM (154cm3m−2 area) plots. The morning soil temperature (0–15cm depth) in coldest week of last year experimentation under FYM20 plots was moderated by 0.60 and 0.47°C than NPK and INM plots, respectively. Successive increase of FYM level improved soil organic C, microbial colony formation unit, dehydrogenase activity, bulk density and soil cracking surface area and the best values for all soil properties were recorded under FYM20 plots. Application of 20tFYMha−1 produced 54 and 29% higher gardenpea equivalent pod yield of the system than mineral fertilization and INM, respectively. The principal component analysis revealed that soil CEC was the most important property (among the selected soil parameters) contributing to the pod yield. Soil organic carbon markedly improved other soil properties as evident from correlations. Organic production system with FYM 20tha−1 could be recommended for climate resilient sustainable yield and better soil property of gardenpea–french bean cropping system than mineral fertilization and INM in the Indian Himalayan regions.

볏짚 시용에 따른 벼 재배 논에서의 메탄 배출계수 개발에 관한 연구

BACKGROUND: Accurate estimates of total direct emissions from croplands on a country scale are important for global budgets of anthropogenic sources of emissions and for the development of effective mitigation strategies. Methane production resulted by the anaerobic decomposition of organic compounds where acts as inorganic electron acceptor. This process could be affected by the addition of rice straw, water management and rice variety itself. METHODS AND RESULTS: Rice (Oryza sativa L. Japonica type, var Samkwangbyeo) was cultivated in four plots: (1) Nitrogen-Phosphorus-Potassium (NPK) (:90-45-57 kg/ha); (2) NPK plus 3 Mg/ha rice straw (RS3); (3) NPK plus 5 Mg/ha rice straw (RS5); (4) NPK plus 7 Mg/ha rice straw (RS7) for 3 years (2010-2012) and the rice straw incorporated in fall (Nov.) in Gyeonggi-do Hwaseong-si. Gas samples were collected using the closed static chamber which were installed in each treated plot of . According to application of 3, 5, 7 Mg/ha of rice straw, methane emission increased by 46, 101, 190%, respectively, compared to that of the NPK plot. CONCLUSION(S): We obtained a quantitative relationship between emission and the amount of rice straw applied from rice fields which could be described by polynomial regression of order 2. The emission scaling factor estimated by the relationship were in the range of IPCC GPG (2000).

Long-term effect of nutrients on castor (Ricinus communis L.) productivity, soil fertility, nutrient uptake and nutrient-use efficiency in rainfed Alfisols

A fixed-plot field experiment was conducted since 2005 to study the long-term effect of nutrients on the productivity, soil fertility, nutrient uptake and nutrient-use efficiency of castor (Ricinus communis L.) in castorsorghum (Sorghum bicolor) cropping system in rainfed Alfisols of Andhra Pradesh. Application of recommended dose offertilizers, RDF (60-40-30 kg NPK/ha) + 5 t/ha farm yard manure (FYM) recorded significantly higher yield attributes, seed (1645 kg/ha) and oil yield (817 kg/ha) of castor compared to RDF (1306 kg/ha) but was comparable with integrated use of 75 % NPK + 25 % N through FYM (1427 kg/ha). Imbalanced application of N alone or NP or 50 % NPK and control plots recorded significantly the lowest castor seed yields. At the end of six years of cropping (2011), the treatment RDF-NPK + 5 t/ha FYM significantly improved the soil organic carbon (0.38 %) and resulted in a positive balance of 42, 12.4 and 80 kg/ha of available soil N, P and K besides improving the nutrient uptake of castor (65.1, 10.63 and 33.2 kg/ha of N, P and K, respectively). Agronomic efficiency of nutrients (N, P and K) was found higher in the treatment, 75 % RDF + 25 % N through FYM. However, apparent recovery of N, P and K was highest in NPK + 5 t/ha FYM treatment.

Prévalence de l’hypertension artérielle pulmonaire au cours du lupus érythémateux systémique

Sustainability of agricultural systems has become an important issue all over the world. Hence, sustainability and climate resilience of gardenpea–french bean cropping system was evaluated by yield trends, C sequestration and emission reduction and soil properties as affected by four application rates of farmyard manure (FYM) (5–20 t ha−1) vis-à-vis mineral fertilization, integrated nutrient management (INM) practices as 50% recommended NPK + FYM at 5 t ha−1 and un-amended control after six years of cropping in the Indian Himalayas. The highest sustainable yield index of 0.606 was achieved with the application of 20 t FYM ha−1 (FYM20). The carbon sequestration potential of FYM20 plots was about 459 and 193% more than NPK and INM plots, respectively. The same plots reduced 53 and 24% carbon equivalent emission with comparison to NPK and INM application, respectively. The soil cation exchange capacity (CEC) under FYM20 plots was 22 and 11% higher than NPK and INM plots. The soil cracking volume under FYM20 plots (57 cm3 m−2 area) was very less compared to NPK (324 cm3 m−2 area) and INM (154 cm3 m−2 area) plots. The morning soil temperature (0–15 cm depth) in coldest week of last year experimentation under FYM20 plots was moderated by 0.60 and 0.47 °C than NPK and INM plots, respectively. Successive increase of FYM level improved soil organic C, microbial colony formation unit, dehydrogenase activity, bulk density and soil cracking surface area and the best values for all soil properties were recorded under FYM20 plots. Application of 20 t FYM ha−1 produced 54 and 29% higher gardenpea equivalent pod yield of the system than mineral fertilization and INM, respectively. The principal component analysis revealed that soil CEC was the most important property (among the selected soil parameters) contributing to the pod yield. Soil organic carbon markedly improved other soil properties as evident from correlations. Organic production system with FYM 20 t ha−1 could be recommended for climate resilient sustainable yield and better soil property of gardenpea–french bean cropping system than mineral fertilization and INM in the Indian Himalayan regions.

Nutrient enrichment increased species richness of leaf litter fungal assemblages in a tropical forest

Microbial communities play a major role in terrestrial ecosystem functioning, but the determinates of their diversity and functional interactions are not well known. In this study, we explored leaf litter fungal diversity in a diverse Panama lowland tropical forest in which a replicated factorial N, P, K and micronutrient fertilization experiment of 40 × 40 m plots had been ongoing for nine years. We extracted DNA from leaf litter samples and used fungal-specific amplification and a 454 pyrosequencing approach to sequence two loci, the nuclear ribosomal internal transcribed spacer (ITS) region and the nuclear ribosomal large subunit (LSU) D1 region. Using a 95% sequence similarity threshold for ITS1 spacer recovered a total of 2523 OTUs, and the number of unique ITS1 OTUs per 0.5-1.0 g leaf litter sample ranged from 55 to 177. Ascomycota were the dominant phylum among the leaf litter fungi (71% of the OTUs), followed by Basidiomycota (26% of the OTUs). In contrast to our expectations based on temperate ecosystems, long-term addition of nutrients increased, rather than decreased, species richness relative to controls. Effect of individual nutrients was more subtle and seen primarily as changes in community compositions especially at lower taxonomic levels, rather than as significant changes in species richness. For example, plots receiving P tended to show a greater similarity in community composition compared to the other nutrient treatments, the +PK, +NK and +NPK plots appeared to be more dominated by the Nectriaceae than other treatments, and indicator species for particular nutrient combinations were identified.

호밀이 투입된 오이 시설재배지에서 수량과 토양용액의 질산태질소과의 관계

This study was conducted to estimate the effect of nitrogen reduction by applying ryegrass and to determine the relationship between yield and nitrate concentration of soil solution for cucumber cultivation in plastic film house. Nitrogen levels with recovery of ryegrass () was 0, 50, 75, 100 % of 199 kg N as N recommendation by determining soil EC value. Yield and nitrate concentration in soil solution was investigated during cucumber cultivation. Yields of N treatments applied ryegrass showed 64.3, 70.9, 70.3, and , respectively, it could reduce about 25-50% of nitrogen application compared to yield () of NPK plot applied 199 kg N . Nitrate concentration in soil solution was average 26.0, 30.1, 41.4, during cucumber cultivation and was related between yield and average nitrate concentration of soil solution following as; (). However, it needs to conduct extra-experiment due to high variation of nitrate concentration during cultivation periods.

Crop response and soil fertility as influenced by green leaves of indigenous agroforestry tree species in a lowland rice system in northeast India

Field experiments were conducted during rainy seasons of three consecutive years (2008–2010) to study the effect of green leaf manuring on dry matter partitioning and productivity of lowland rice (Oryza sativa L.). Green leaves of five indigenous agroforestry tree species viz., Erythrina indica, Acacia auriculiformis, Alnus nepalensis, Parkia roxburghii, and Cassia siamea were treated at 10 t ha−1 on fresh weight basis in rice fields and compared with recommended N–P2O5–K2O (80:60:40 kg ha−1) and control treatments. During 2008–2009 year, yield attributes and rice yield were greater in NPK plots as compared to the green-leaf manured ones. However, in the third year, green leaf manuring (except that of Alnus) surpassed even the recommended N–P2O5–K2O treatment in terms of dry matter production and yield; better response was however observed with Erythrina. The soil available N after final harvest increased by ca. 14–20 % in Alnus and Erythrina treated plots as compared to the control. Over all, it could be said that management of plant residues can have long-term implications apart from the desired maintenance of soil organic matter and improving crop yield.

Effects of contrasting soil management regimes on total and labile soil organic carbon fractions in a loess soil in China

Labile soil organic carbon pools are valuable indicators of soil quality, early changes in soil total organic carbon (TOC) stocks, and (hence) changes in soil carbon sequestration pools and dynamics induced by changes in soil management practices. To improve the management of loess soils in China, we have examined effects of soil and nutrient management treatments applied in a 20-year experiment on TOC and the following fractions: particulate organic carbon (POC), light fraction organic carbon (LFOC), microbial biomass carbon (MBC) and permanganate oxidizable carbon (KMnO4 C). The soil management regimes were cropland abandonment (Abandonment), bare fallow without vegetation (Fallow) and a wheat-maize cropping system (Cropping). Cropping was combined with the following nutrient management treatments: control (CK, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PK), NP, NPK, straw plus NPK (SNPK) and two levels of manure (M, 13.7 and 20.6tha−1) plus NPK (M1NPK and M2NPK). After 20years, the Fallow treatment resulted in significantly lower TOC by 22% and labile C fractions by 29%–43% except MBC than Cropping, while Abandonment markedly increased all labile C fractions by 43%–64% except POC relative to Cropping, but the Abandonment and Cropping regimes resulted in similar TOC contents (10.75gkg−1 and 10.16gkg−1, respectively). Of the four C fractions, LFOC and KMnO4 C were the most sensitive indicators of changes in TOC induced by the soil management regimes. Under Cropping, TOC contents were similar in NP, NPK and SNPK plots, and significantly higher than those in CK plots (by 34%, 32% and 45%, respectively). Manure addition further enhanced TOC contents, which were highest following the M2NPK treatment (13.88gkg−1). Labile C fractions were also significantly higher following the treatments including organic amendment than following applications solely of chemical fertilizers, except that the SNPK, NP and NPK treatments resulted in similar LFOC contents. Application solely of chemical fertilizers had no significant effects on LFOC and KMnO4 C fractions compared with CK. Nevertheless, application of NP or NPK significantly increased contents of POC and MBC relative to CK (by 115% and 90% or 31% and 53%, respectively). Thus, LFOC and KMnO4 C fractions were not sensitive indicators of changes in TOC induced by mineral nutrient management practices under current conditions. Overall, given the minor differences between the effects of the NP and NPK treatments, application of manure and NP appears to be the most suitable management practice for improving TOC sequestration in the loess soil.

시설상추 재배시 축분퇴비 이용에 따른 화학비료 절감효과 평가

Livestock manure compost (LC) generally contains high content of phosphorus, therefore can be a substitute for phosphorus fertilizers. In this experiment of the cultivation of lettuce in green house, the possibility of LC as a subsitute for phosphorus fertilizer was investigated and the fertilizer efficiency of nitrogen and potassium in LC as compared with chemical N fertilizer (urea) and K fertilizer (potassium chloride) was examined. In proportion to the increase in the application rate of nitrogen fertilizer, soil pH declined, whereas EC and -N content became higher. The application of LC appeared to increase the soil content of organic matter, available phosphate, exchangeable calcium, magnesium and sodium more than that of chemical fertilizer. Supplementation of the K fertilizer by the lack amount from the application of LC resulted in the same exchangeable potassium content in soil with NPK plot in which N, P and K fertilizers were applied by the amount of soil test recommendation. The relationship between soil -N content and nitrogen application rate from fertilizer and compost showed as y=0.57717a+0.19760b+74.65 (=0.6347) in which y is the soil -N content (mg ), a is nitrogen application rate from fertilizer and b is nitrogen application rate from compost (kg ), respectively. From this equation, the supply ability of -N into soil of LC exhibited about 34% (pig manure compost 37.0, chicken manure compost 34.7, cattle manure compost 23.3) of nitrogen fertilizer (urea).

Net annual global warming potential and greenhouse gas intensity in Chinese double rice-cropping systems: a 3-year field measurement in long-term fertilizer experiments

The impact of agricultural management on global warming potential (GWP) and greenhouse gas intensity (GHGI) is not well documented. A long-term fertilizer experiment in Chinese double rice-cropping systems initiated in 1990 was used in this study to gain an insight into a complete greenhouse gas accounting of GWP and GHGI. The six fertilizer treatments included inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), and balanced inorganic fertilizer (NPK)], combined inorganic/organic fertilizers at full and reduced rate (FOM and ROM), and no fertilizer application as a control. Methane (CH4) and nitrous oxide (N2O) fluxes were measured using static chamber method from November 2006 through October 2009, and the net ecosystem carbon balance was estimated by the changes in topsoil (0–20 cm) organic carbon (SOC) density over the 10-year period 1999–2009. Long-term fertilizer application significantly increased grain yields, except for no difference between the NK and control plots. Annual topsoil SOC sequestration rate was estimated to be 0.96 t C ha−1 yr−1 for the control and 1.01–1.43 t C ha−1 yr−1 for the fertilizer plots. Long-term inorganic fertilizer application tended to increase CH4 emissions during the flooded rice season and significantly increased N2O emissions from drained soils during the nonrice season. Annual mean CH4 emissions ranged from 621 kg CH4 ha−1 for the control to 1175 kg CH4 ha−1 for the FOM plots, 63–83% of which derived from the late-rice season. Annual N2O emission averaged 1.15–4.11 kg N2O–N ha−1 in the double rice-cropping systems. Compared with the control, inorganic fertilizer application slightly increased the net annual GWPs, while they were remarkably increased by combined inorganic/organic fertilizer application. The GHGI was lowest for the NP and NPK plots and highest for the FOM and ROM plots. The results of this study suggest that agricultural economic viability and GHGs mitigation can be simultaneously achieved by balanced fertilizer application.

Effect of zinc foliar application on grain yield of maize and its yielding compone

Actual yields of maize harvested by farmers are at level much below attainable yield potential of currently cultivated varieties. Among many growth factors zinc was recognized as one of main limiting factors of maize crop growth and yielding. This hypothesis has been verified within a three-year field study, where zinc fertilizer was applied to maize plants at the 5&lt;sup&gt;th&lt;/sup&gt; leaf stage. Maize crop responded significantly to zinc foliar application in two of three years of study. The optimal rate of zinc foliar spray for achieving significant grain yield response was in the range from 1.0 to 1.5 kg Zn/ha. Grain yield increase was circa 18% (mean of three years) as compared to the treatment fertilized only with NPK. Plants fertilized with 1.0 kg Zn/ha significantly increased both total N uptake and grain yield. Yield forming effect of zinc fertilizer revealed via improvement of yield structure elements. The number of kernels per plant showed the highest response (+17.8% as compared to the NPK plot) and simultaneously the highest dependence on N uptake (&lt;i&gt;R&lt;/i&gt;&lt;sup&gt;2&lt;/sup&gt; = 0.79). For this particular zinc treatment, however, the length of cob can also be applied as a component of yield structure significantly shaping the final grain yield.

Role of biofertilizer on faba bean growth, yield, and its effect on bean aphid and the associated predators

The role of biofertilizer on parameters of faba growth, nodulation, yield and also its effects on aphid infestation and the associated predators were studied. Field experiments were conducted at the Production and Research Station of National Research Center in El-Nobaria, Egypt in the 2005/06 season. Four treatments were carried out: inoculation with rhizobia alone (R), mixed rhizobia with pseudomonas (R + P), rhizobia + mycorrhiza (R + M) or rhizobia + pseudomonas + mycorrhiza (R + P + M) compared to the fifth treatment with recommended dose of chemical fertilizers NPK (150 kg: 150 kg: 200 kg/ha). There was a significant positive effect of rhizobia strains as evident from fresh and dry weight of leaves and stems, root/shoot ratio, pods/flowers ratio as well as the number and weight of nodules compared to NPK fertilizer plots. A total count of bacteria was higher significantly in mixed inoculant's strains than in single inoculant. Either single or mixed inoculants strains showed positive response on seeds weight compared to NPK plots. The highest number of pods was achieved in treatment of rhizobia mixed with mycorrhiza or pseudomonas. Three treatments were conducted for aphid's control. The percent of aphid reduction caused by aphid-control treatments was Pirimiphos-methyl (98%), m-pede (62%), and NeeemAzal T/S (50%). The mixed inoculants strains caused a good reduction percent of aphid population (71.3%) compared to single inoculation (64%). Therefore, we recommend using the mixed inoculants strains as commercial inocula for improving production of faba bean.

Fertilization effects on yield sustainability and soil properties under irrigated wheat–soybean rotation of an Indian Himalayan upper valley

To date, the sustainability of wheat (Triticumaestivum)–soybean (Glycinemax) cropping systems has not been well assessed, especially under Indian Himalayas. Research was conducted in 1995–1996 to 2004 at Hawalbagh, India to study the effects of fertilization on yield sustainability of irrigated wheat–soybean system and on selected soil properties. The mean wheat yield under NPK + FYM (farmyard manure) treated plots was ~27% higher than NPK (2.4 Mg ha−1). The residual effect of NPK + FYM caused ~14% increase in soybean yield over NPK (2.18 Mg ha−1). Sustainable yield index values of wheat and the wheat–soybean system were greater with annual fertilizer N or NPK plots 10 Mg ha−1 FYM than NPK alone. However, benefit:cost ratio of fertilization, agronomic efficiency and partial factor productivity of applied nutrients were higher with NPK + FYM than NPK, if FYM nutrients were not considered. Soils under NPK + FYM contained higher soil organic C (SOC), total soil N, total P and Olsen-P by ~10, 42, 52 and 71%, respectively, in the 0–30 cm soil layers, compared with NPK. Non-exchangeable K decreased with time under all treatments except NPK. Total SOC in the 0–30 cm soil layer increased in all fertilized plots. Application of NPK + FYM also improved selected soil physical properties over NPK. The NPK + FYM application had better soil productivity than NPK but was not as economical as NPK if farmers had to purchase manure.

Soil organic carbon sequestration in relation to organic and inorganic fertilization in rice–wheat and maize–wheat systems

Soil organic carbon (SOC) pool is the largest among the terrestrial pools. The restoration of SOC pool in arable lands represents a potential sink for atmospheric CO 2. The management and enhancement of SOC is important for sustainable agriculture. The cropping system and soil type influence crop biomass under different fertilization. Data from two long-term field experiments on rice–wheat and maize–wheat systems in progress since 1971, were analyzed to assess the impact of fertilization practices on SOC stocks in sandy loam soils (typic ustipsament). The treatments in rice–wheat included (i) farmyard manure (FYM alone @ 20 t ha −1, applied at the time of pre-puddling tillage), (ii) N 120P 30K 30 (120 kg N, 30 kg P 2O 5 and 30 kg K 2O ha −1), (iii) N 120P 30 (same as in (ii) except that K application was omitted), (iv) N 120 (same as in (ii) except that P and K application was omitted) and (v) control (without any FYM or inorganic fertilizer). Similar treatments were studied in maize–wheat except that the amounts of N, P 2O 5 and K 2O were 100, 50 and 50 kg ha −1, respectively. In rice–wheat system, the SOC concentration at different depths in 0–60 cm soil profile was higher (1.8–6.2 g kg −1) in FYM-treated plots followed by 1.7–5.3 g kg −1 in NPK plots, compared to 0.9–3.0 g kg −1 in unfertilized plots. Balanced fertilization improved the SOC concentration. Similar trend was found in maize–wheat system. In the 60-cm soil profile the total SOC stocks in both the cropping systems were highest in FYM (31.3 and 23.3 Mg ha −1 in rice–wheat and maize–wheat system) followed by balanced fertilization (29.6 and 21.3 Mg ha −1) and lowest in unfertilized control (21.4 and 18.7 Mg ha −1). The SOC concentration in rice–wheat soils was 54 and 30% higher in FYM and NPK plots than in maize–wheat system. Improved SOC content enhances soil quality, reduces soil erosion and degradation, and increases soil. The soils under rice–wheat sequestered 55% higher SOC in FYM plots and 70% higher in NPK plots than in maize–wheat. These results document the capacity of optimally fertilized rice–wheat system to sequester higher C as compared to maize–wheat system.

Survival of bacterial DNA and culturable bacteria in archived soils from the Rothamsted Broadbalk experiment

Dried soil samples from many sources have been stored in archives world-wide over the years, but there has been little research on their value for studying microbial populations. Samples collected since 1843 from the Broadbalk field experiment on crop nutrition at Rothamsted have been used to document changes in the structure and composition of soils as agricultural practices evolve, also offering an invaluable record of environmental changes from the pre- to post-industrial era in the UK. To date, the microbial communities of these soils have not been studied, in part due to the well-documented drop in bacterial culturability in dried soils. However, modern molecular methods based on PCR amplification of DNA extracted directly from soil do not require bacterial cells to be viable or intact and may allow investigations into the legacy of bacteria that were present at the time of sample collection. In a preliminary study, to establish if dried soils can provide a historical record of bacterial communities, samples from the Broadbalk soil archive dating back to 1868 were investigated and plots treated with either farmyard manure (FYM) or inorganic fertilizer (NPK) were compared. As anticipated, the processes of air-drying and milling greatly reduced bacterial viability whilst DNA yields declined less and may be preserved by desiccation. A higher proportion of culturable bacteria survived the archiving process in the FYM soil, possibly protected by the increased soil organic matter. The majority of surviving bacteria were firmicutes, whether collected in 2003 or in 1914, but a wide range of genera was detected in DNA extracted from the samples using PCR and DGGE of 16S rRNA genes. Analysis of DGGE band profiles indicated that the two plots maintained divergent populations. Sequence analysis of bands excised from DGGE gels, from a sample collected in 1914, revealed DNA from α- and β-proteobacteria as well as firmicutes. PCR using primers specific for ammonia oxidizing bacteria showed similar band profiles across the two treatments in recently collected samples, however older samples from the NPK plot showed greater divergence. Primers specific for the genus Pseudomonas were designed and used in real-time quantitative PCR to indicate that archived soil collected in 1868 contained 10-fold less pseudomonad DNA than fresh soil, representing around 10 5 genomes g −1 soil. Prior to milling, dramatically less pseudomonad DNA was extracted from recently collected air-dried soil from the NPK compared to the FYM plot; otherwise, the two plots followed similar trends. Overall bacterial abundance, diversity and survival during the archiving process differed in the two soils, possibly due to differences in clay and soil organic matter content. Nevertheless, the results demonstrate that air-dried soils can protect microbial DNA for more than 150 years and offer an invaluable resource for future research.

Significance of Transients in Soil Temperature Series

The primary objective of this study was to investigate the impact of observation scale on the estimation of soil thermal properties. Transients are usually filtered out and ignored when classical Fourier approaches are used to deconstruct and model temperature time series. It was hypothesized that examination of such transients may be more important in identifying and quantifying short-term perturbations in internal soil heat transfer induced by agronomic disturbances. Data-logged temperatures were collected at 10-minute intervals from thermistor probes installed at 10 and 25 cm depths in isolated areas of two grassed plots. One plot (6T) had been treated twice with 6 Mg ha −1 composted turkey litter as received. The other plot (NPK) was fertilized at the same time with NPK fertilizer. Various methods were used to analyze the series to obtain apparent soil thermal diffusivity ( D-value) at various time scales. Results supported the hypothesis that short-term differences in internal soil heat transfer between the 6T and NPK plots were more manifest and effectively captured by estimated D-values calculated from the monthly and daily partial series. The 6T plot had higher soil organic matter content than the NPK plot and had lower apparent soil thermal diffusivity. Diurnal soil temperature amplitudes, required to calculate the mean D-values from partial series, were more effectively obtained using a temperature change rate method. The more commonly used Fourier analysis tended to be effective for this purpose when the partial series reasonably presented well-defined diurnal patterns of increasing and decreasing temperatures.