Long-term Use of Balanced and Integrated Nutrient Management Improved Soil Aggregation and Carbon Stabilization in a Maize-wheat Cropping Sequence

Sustainable nutrient management practices have the potential to enhance carbon (C) storage capacity of agricultural soils that may help offset increasing atmospheric CO2 concentration. Nutrient management practices on long-term basis differentially influence aggregates and distribution of soil organic C (SOC) present within aggregates, which in time may affect C stabilization. The present study assessed the impact of long-term application of fertilizers for 44 years either alone or integration with farmyard manure (FYM) on bulk density, SOC and C pools, potassium permanganate oxidizable C (KMnO4), aggregate stability and distribution of C fractions within different size aggregate under maize-wheat cropping sequence. The application of 100%NPK+FYM significantly (P< 0.05) improved soil aggregation and mean weight diameter (MWD). The percent of macro-aggregates (MacroA) and meso-aggregates (MesoA) was maximum in 100%NPK+FYM followed by NPK and the minimum in the control treatment. Irrespective of aggregate classes, TOC (g kg-1 aggregate) was maximum in 100%NPK+FYM treatment with an average of 8.42 g kg-1 aggregate as compared to control (5.05 g kg-1 aggregate). If averaged across the treatments, TOC concentration in aggregates followed the order MacroA> MesoA>MicroA. Correspondingly, results for KMnO4-C were similar in different treatments and aggregate classes. Application of FYM with inorganic fertilizers (NPK) or NPK showed a significant increase in all oxidizable organic C fractions particularly recalcitrant C fraction, which reflects the stable nature of OC as compared to very labile and labile C fractions. In general, C present in mineral fraction and large-sized aggregates (MacroA) has higher recalcitrant fractions of SOC as compared to small-sized aggregates (MesoF and MicroF). The study concluded that long-term balanced and integrated nutrient management improved soil aggregation, C distribution within aggregates, and C storage capacity of soils under maize-wheat. Carbon associated with macro aggregate and a mineral fraction has more recalcitrant C fraction compared to meso and micro aggregate fractions.

Effect of nitrogen application through urea and Azolla on yield, nutrient uptake of rice and soil acidity indices in acidic soil of Meghalaya

Aim: To investigate the effect of nitrogen application through urea and Azolla on yield, nutrient uptake of rice (Oryza sativa L.) cv. Shasharang and to assess the improvement in soil acidity indices in acidic soil of Meghalaya.Methodology: A field experiment was conducted with six treatments viz., control (T1), Azolla incorporation @ 1.6 tonnes ha-1 (T2), 30 kg N ha-1 through urea (T3), 60 kg N ha-1 through urea (T4), 30 kg N ha-1 through urea + Azolla incorporation @ 1.6 tonnes ha-1 (T5) and 60 kg N ha-1 through urea with Azolla incorporation @ 1.6 tonnes ha-1 (T6). The experiment was laid out in RBD and replicated four times. The physico-chemical properties of the experimental soil were pH 5.1, SOC 1.75 percent, available N, P and K as 288.62, 17.23 and 201.46 kg ha-1, respectively. Results: The application of 60 kg N ha-1 through urea along with Azolla incorporation @ 1.6 tonnes ha-1 (T6) recorded highest dry matter i.e. 58. 15 g hill-1 at maturity of rice. Similarly, 60 kg N ha-1 through urea with Azolla incorporation @ 1.6 tonnes ha-1 produced highest grain and straw yield i.e. 4.2 t ha-1 and 7.68 t ha-1 followed by T5 and T4. The magnitude of increase in N, P and K concentration and uptake in grain was 28.57, 97.02; 26.09, 84.21 and 15.69, 76.47 percent in T6 over T1. The analysis of soil acidity indices indicated that highest improvement in pH was observed in T2 over all other treatments. Further, pH increased significantly in the treatments receiving Azolla incorporation (T2, T5 and T6) compared with the sole application of urea/control (T1, T3 and T4). The exchangeable calcium and magnesium (meq 100 g-1), CEC (meq 100 g-1) and base saturation percentage also showed the same trends and the highest values were observed as 1.92, 7.90 and 24.30 in T2. However, in contrast to this, the lowest values of exchangeable aluminium, exchangeable acidity and acidity saturation percentage were observed in T2 indicating that the sole application of Azolla improved soil acidity indices. Interpretation: It may be concluded from the present study that Azolla-urea nitrogen system may be suitable for getting optimum production of rice under tropical conditions and improving soil acidity indices because of its ability to fix atmospheric nitrogen.

Assessing nitrogen flow in production and utilization cycle of wheat and maize as a tool to monitor N loss in Iran / Avaliação do fluxo de nitrogênio na produção e utilização do ciclo do trigo e do milho como uma ferramenta para monitorar as perdas de N em agro-ecossistema iraniano

Increasing resource use efficiency is crucial for enhancement of agricultural productions and reducing environmental hazards. For this purpose, improvement of Nitrogen use efficiency is an effective approach. Not only N loss occurs in field but also in processing course of food utilization. The objective of this study was to evaluate N loss and efficiency from production to consumption for wheat and maize. For this purpose, data for the amount of applied nitrogen, acreage, yields, amount of returned residue were collected and a proportion of N allocated to different source of food or feed was also traced. Results showed that total N harvested by wheat and maize were 387 and 81.7 kt and N use efficiency for the same crops were 25 and 60%, respectively. Efficiency of N harvested by the crops was different based on the path used. Total N use efficiency in food production cycle for wheat and maize were 14.2 and 7.6%, respectively. Higher efficiency of N was observed in plant food production compared with animal feed. In general, N use efficiency in plant food production system was about 13 times higher than that of feed. For decreasing N loss in food production system, efficiency should be increased in the field and processing courses.

Aumentar a eficiência na utilização dos recursos é crucial para a valorização das produções agrícolas e reduzir os riscos ambientais. Para este efeito, a melhoria da eficiência de utilização de azoto é um método eficaz. Não apenas perdas de N acontecem em campo, mas também no processamento decurso de utilização dos alimentos. O objetivo deste estudo foi avaliar as perdas de N e eficiência da produção ao consumo de trigo e milho. Para esses dados de propósito para a quantidade de nitrogênio aplicado, a área, o rendimento, a quantidade de resíduos devolvidos foram coletadas e uma proporção de N alocado para outra fonte de alimento ou ração também foi rastreado. Os resultados mostraram que o total de N colhido por trigo e milho foram 387 e 81.7 kte. A eficiência de utilização para as mesmas culturas foram de 25 e 60%, respectivamente. Eficiência de N colhidas pelas culturas foi diferente com base no caminho que foi utilizado. A eficiência total de N utilização no ciclo de produção de alimentos para o trigo e de milho foram 14,2 e 7,6%, respectivamente. Maior eficiência de N foi observada na produção de alimentos planta em comparação com rações para animais. Em geral, N eficiência de utilização em planta do sistema de produção de alimentos foi de cerca de 13 vezes maior do que a de alimentos para animais. Para diminuir as perdas de nitrogênio no sistema de produção de alimentos, a eficiência deve ser aumentada nos cursos de campo e de processamento.

Digestibilidade do fósforo em dietas como estratégia nutricional para redução de efluentes da tilapicultura / Digestibility of phosphorus in feed as a nutritional strategy for reduce of effluents from tilapia culture

Avaliou-se a digestibilidade do fósforo em dietas isoproteicas e isoenergéticas contendo 28 por cento de proteína bruta e 3000kcal de ED/kg com porcentagens de 0,8 e 1,2 por cento de fósforo total para juvenis de tilápia-do-nilo (Oreochromis niloticus). Os parâmetros de qualidade da água apresentaram diferenças significativas (P<0,05) para o fósforo total, ortofosfato, DBO5 e condutividade. A digestibilidade das dietas foi de 75,3 por cento para os peixes alimentados com 0,8 por cento de fósforo total e de 77,5 por cento para os alimentados com 1,2 por cento de fósforo total. As taxas de eficiência da absorção do fósforo foram de 74,8 por cento e 76,3 por cento para as tilápias alimentadas com 0,8 por cento e 1,2 por cento de fósforo, respectivamente. O aumento do percentual de 0,4 por cento de fósforo na dieta levou ao acréscimo de 55 por cento de fósforo na água. Dessa forma, a utilização de valores abaixo de 0,8 por cento de fósforo total é uma estratégia que auxilia na redução do impacto causado pelos efluentes oriundos da criação de peixes, sem comprometer a eficiência do aproveitamento das dietas pelas tilápias.

The objective of this study was to evaluate the digestibility of phosphorus in isonitrogenous and isocaloric diets containing 28 percent crude protein and 3000kcal DE/kg at different levels of total phosphorus, 0.8 percent and 1.2 percent, in Nile tilapia juveniles (Oreochromis niloticus). The water quality parameters presented significant differences (P<0.5) for total phosphorus, orthophosphate, BOD5 and conductivity. The digestibility of diets was 75.3 percent for fish fed 0.8 percent total phosphorus and 77.5 percent for treatment with 1.2 percent total phosphorus. It was observed that the efficiency rate in phosphorus absorption among the treatments was 74.3 and 76.3 percent for tilapia fed 0.8 percent and 1.2 percent phosphorus, respectively. It can be concluded that a percentage increase of 0.4 percent phosphorus in tilapia diets contributes to the increase of 55 percent of phosphorus in water and the lower phosphorus input in the diet can be a nutritional strategy to be practiced. Thus, it will help to reduce the impact caused by effluents from fish farming, without lowering the efficiency of tilapia diet utilization.

Conservation tillage, optimal water and organic nutrient supply enhance soil microbial activities during wheat (Triticum Aestivum L.) cultivation

The field experiments were conducted on sandy loam soil at New Delhi, during 2007 and 2008 to investigate the effect of conservation tillage, irrigation regimes (sub-optimal, optimal and supra-optimal water regimes), and integrated nutrient management (INM) practices on soil biological parameters in wheat cultivation. The conservation tillage soils has shown significant (p<0.05) increase in soil respiration (81.1 percent), soil microbial biomass carbon (SMBC) (104 percent) and soil dehydrogenase (DH) (59.2 percent) compared to the conventional tillage soil. Optimum water supply (3-irrigations) enhanced soil respiration over sub-optimum and supra-optimum irrigations by 13.32 percent and 79 percent respectively. Soil dehydrogenase (DH) activity in optimum water regime has also increased by 23.33 percent and 8.18 percent respectively over the other two irrigation regimes. Similarly, SMBC has also increased by 12.14 percent and 27.17 percent respectively in soil with optimum water supply compared to that of sub-optimum and supra-optimum water regime fields. The maximum increase in soil microbial activities is found when sole organic source (50 percent Farm Yard Manure+25 percent biofertilizer+25 percent Green Manure) has been used in combination with the conservation tillage and the optimum water supply. Study demonstrated that microbial activity could be regulated by tillage, water and nitrogen management in the soil in a sustainable manner.