Morphological responses among crop species to full-season exposures to enhanced concentrations of atmospheric CO2 and O3

Field studies using open-top chambers were conducted at USDA-BARC involving the growth of soybeans ('89 & '90), wheat ('91 & '92), and corn ('91), under increased concentrations of atmospheric CO₂ and O₃. Treatment responses were compared in all cases to plants grown in charcoal-filtered (CF) air (seasonal 7-h mean = 25±3 n mol O₃ mol^–1) having 350 or 500 mol CO₂ mol^–1. Elevated seasonal O₃ levels for the soybean, wheat, and corn studies averaged 72.2±4, 62.7±2, and 70.2 n mol O₃ mol^–1, respectively. Results presented were obtained for plants grown in silt loam soil under well-watered conditions. Grain yield increases in response to elevated CO₂ in the absence of O₃ stress averaged 9.0, 12.0, and 1.0% for soybean, wheat, and corn; respectively. Reductions in grain yields in response to the elevated O₃ treatments at 350 mol CO, mol^–1 averaged 20.0, 29.0 and 13.0% for soybean, wheat, and corn, respectively. Reductions in grain yields in response to elevated O₃ at 500 mol CO₂ mol^–1 averaged 20.0, 8.0, and 7.0% for soybean, wheat, and corn, respectively. Dry biomass and harvest index in wheat were significantly reduced by O₃ stress at 350 mol mol ¹ CO₂ but not at 500 u mol mol^–1 CO₂. Seed weight 1000^–1 for scybeans and wheat was significantly increased by CO₂ enrichment and decreased by O₃ stress. Seed weight 1000^–1 in corn was increased by O₃ stress suggesting that O₃ affected pollination resulting in fewer kernels per ear.Scientific Article No. A7784, Contribution No. 9105, Maryland Agric. Exp. Sta., Univ. of MD, College Park, MD 20472     

Starter fertilizer effects on grain sorghum hybrids grown on a soil high in residual phosphorus in a no‐tillage environment

Conservation tillage crop production systems have become common in the central Great Plains because they reduce soil erosion and increase water‐use efficiency. The high residue levels associated with no‐tillage systems can cause soils to be cool and wet which can reduce nutrient uptake and growth of crops. Starter fertilizer applications have been effective in improving nutrient uptake even on soils high in available nutrient elements. Resent research indicates that corn (Zea mays L.) hybrids differ in their responses to starter fertilizer. No information is currently available concerning grain sorghum [Sorghum bicolor (L.) Moench] hybrid response to starter fertilizer. The objective of this study was to evaluate grain sorghum hybrid responses to starter fertilizer in a no‐tillage environment on a soil high in available phosphorus (P). This field experiment was conducted from 1995 to 1997 at the North Central Kansas Experiment Field, located near Belleville, on a Crete silt loam soil (fine, montmorillonitic, mesic, Pachic Arguistoll). Treatments consisted of 12 grain sorghum hybrids and two starter fertilizer treatments. Fertilizer treatments were starter fertilizer [34 kg nitrogen (N) and 34 kg P₂O₅ ha^‐1] or no starter fertilizer. Starter fertilizer was applied 5 cm to the side and 5 cm below the seed at planting. Immediately after planting, N was balanced on all plots to give a total of 168 kg N ha^‐1. In all three years of the experiment, grain yield, total P uptake (grain plus stover), grain moisture content at harvest, and days to mid‐bloom were affected by a hybrid x starter fertilizer interaction. Starter fertilizer consistently increased yields, reduced harvest grain moisture, improved total P uptake, and reduced the number of days needed from emergence to mid‐bloom of Pioneer 8505, Pioneer 8522Y, Pioneer 8310, Dekalb 40Y, Dekalb 48, Dekalb 51, Dekalb 55, and Northrup King 524, buthadno effect on Pioneer 8699, Dekalb 39Y, Northrup King 383Y, and Northrup King 735. When averaged over the three years, starter fertilizer increased grain yield of responding hybrids (hybrids in which the 3‐year average grain yield was significantly increased by the application of starter fertilizer) by 920 kg ha^‐1. In responding hybrids, starter fertilizer reduced grain moisture at harvest by 54 g kg¹ and also shortened the period from emergence to mid‐bloom by five days. Starter fertilizer increased V6 stage aboveground dry matter production and N and P uptake of all hybrids tested. Results of this work show that in high residue production systems even on soils high in available P, starter fertilizer can consistently increase yield of some hybrids, whereas other hybrids are not affected.     

Effects of phosphorus application method and rate on furrow‐irrigated ridge‐tilled grain sorghum

Conservation tillage systems, including ridge‐tillage, have become increasing popular with producers in the central Great Plains because of their effectiveness in controlling soil erosion and conserving water. A major disadvantage of the ridge system is that nutrient placement options are limited by lack of any primary tillage options. The objective of this research was to investigate the effects of method of phosphorus (P) placement and rate on irrigated grain sorghum [Sorghum bicolor (L.) Moench] grown in a ridge‐tillage system on a soil low in available P. This experiment was conducted from 1993 to 1995 on a producer's field near the North Central Kansas Experiment Field at Scandia, Kansas on a Carr sandy loam soil (course, loamy, mixed, calcareous, mesic, Typic Udifuvents). Treatments consisted of fertilizer application methods, surface broadcast, single band starter (5 cm to the side and 5 cm below seed), dual band starter (one band on each side of the row), and knifed in the center of the row middle (38 cm from each adjacent row). Each of these treatments was made at either 22 or 44 kg P₂O₅ ha^‐1, and nitrogen (N) also was included at the rate of 13 kg ha^‐1. Additional treatments were, a combination of 13 kg N and 44 kg P₂O₅ ha^‐1 applied half broadcast and half as a single band starter, a 1:1 N:P₂O₅ ratio (44 kg N and 44 kg P₂O₅ ha^‐1) applied as a single band starter, and a 3:1 ratio (134 kg N and 44 kg P₂O₅ ha^‐1) applied as a single band starter. A no‐P check plot also was included. Broadcast and center‐of‐row middle knife applications were made approximately 1 week before planting. After planting, N was balanced on all plots to give a total of 180 kg ha^‐1. Applied P treatments improved grain yield and nutrient uptake and consistently shortened the time from emergence to mid‐bloom in all 3 years of the experiment. On this low soil test P soil, treatments that subsurface banded P increased grain yield by 1.27 Mg ha^‐1 compared to broadcast treatments. Placing N and P in a single starter band 5 cm to the side and 5 cm below the seed was as effective as placing a band on each side of the row. Knife applying N and P in the center of the row was not as effective as placement beside the row. Single band starter application of N and P in a 1:1 and or 3:1 N:P₂O₅ ratio consistently increased yields and nutrient uptake and shortened the time to mid‐bloom as compared to the single band starter treatment that provided only 13 kg N ha^‐1. Over the 3 years of the study, these 1:1 and 3:1 N:P₂O₅ ratio starters were clearly superior to an other treatments.     

Phosphorous and Mung Bean Residue Incorporation Improve Soil Fertility and Crop Productivity in Sorghum and Mungbean-Lentil Cropping System

ABSTRACT

In sorghum and mungbean – lentil cropping system, field experiments were conducted for three successive years to assess the effect of mung bean residue incorporation on sorghum and succeeding lentil productivity along with different doses of phosphorus (P; 0, 30, 60 kg ha^{? 1}) applied to these crops. The level of soil fertility was also tested with or without incorporation of mung bean residue. The interaction of phosphorus to mungbean residue incorporation was thus studied in relation to improve crop productivity with balancing fertilizer requirements through an eco-friendly approach. Sorghum grain yield increased significantly when 60 kg P₂O₅ ha^{? 1} was applied and mungbean residue incorporated. The response was reduced to 30 kg P₂O₅ ha^{? 1} when mungbean residue was not incorporated. The succeeding lentil crop responded up to 60 kg P₂O₅ ha^{? 1} only when preceding sorghum crop received 0 or 30 kg P₂O₅ ha^{? 1}. Response to applied P₂O₅ to lentil reduced to 30 kg ha^{? 1} when preceding sorghum crop received 60 kg P₂O₅ ha^{? 1} and mungbean residue incorporated. Available soil nitrogen, phosphorus, and organic carbon content increased when mungbean residue was incorporated; however, available potassium (K) of the soil decreased from its initial value.     

Cultivar-Specific Response of Soybean (Glycine max L.) to Ambient and Elevated Concentrations of Ozone Under Open Top Chambers

Two cultivars of soybean (Pusa 9814 and Pusa 9712) were investigated to evaluate the impact of ambient and elevated concentrations of ozone (O₃) in a suburban site of India with and without application of 400 ppm ethylenediurea (EDU) in open top chambers having filtered air (FCs), non-filtered air (NFCs), and non-filtered plus 20 ppb O₃ (NFCs?+?20 ppb). Significant reductions were observed in various growth parameters, biomass accumulation, and yield attributes of soybean cultivars due to ambient O₃ in NFCs and elevated concentration of O₃ in NFCs?+?20 ppb. Reductions in all parameters were of lower magnitude in plants treated with EDU as compared to non-EDU treated plants. Yield (weight of seeds plant^?1) increased by 29.8% and 33% in Pusa 9712 and by 28.2% and 29.0% in Pusa 9814 due to EDU treatment in plants grown at ambient and elevated levels of O₃, respectively. The results clearly showed that (a) EDU can be effectively used to assess phytotoxicity of O₃ by providing protection against its deleterious effects, (b) EDU can be used for biomonitoring of O₃ in areas experiencing its higher concentrations, and (3) EDU is more effective against higher concentrations of O₃.     

Impact of in-season split application of nitrogen on intra-panicle grain dynamics,grain quality,and vegetative indices that govern nitrogen use efficiency in sorghum

Background

The correct rate and timing of nitrogen (N) has the potential to improve sorghum productivity through modified grain yield components and quality. The impacts of in-season split application of N have little documentation.

Aim

An experiment was conducted to determine the optimum rate and timing of N to relate vegetative indices that govern nitrogen use efficiency and to maximize grain yield and quality under different soil types.

Methods

Pioneer 86P20 was grown in three environments on two different soil types following a completely randomized block design with nine N application treatments. Treatments included differing N rates applied at critical developmental stages of sorghum (planting, panicle initiation, and booting), accompanied with high temporal aerial phenotyping.

Results

Opportunities to increase grain protein content while using split N applications were observed, with panicle initiation identified as a critical developmental stage. In-season split application of N enhances grain yield under low soil mineral N. Split application of 31 kg N ha⁻¹ each at the time of planting, panicle initiation, and booting emerged as optimum N treatment to increase protein content in sorghum. Vegetative indices, that is, normalized difference vegetation index and normalized difference red edge index are capable of predicting grain yield and protein content, respectively. Intra-panicle grain numbers and weights were altered significantly at different portions within panicles, with an opportunity to enhance yield potential at the bottom portion. The strong stay-green trait in this hybrid locked a large proportion of nitrogen in the leaves, which warrants the need for balancing stay-green and senescence in sorghum improvement programs.

Conclusions

Findings highlight that in grain sorghum remobilization of residual leaf N into grain is a target to increase yield and grain quality. An optimized stay-green trait balanced with senescence is recommended for enhancing sorghum yield potential.     

Interactive effects of in situ rainwater harvesting techniques and fertilizer sources on mitigation of soil moisture stress for sorghum (Sorghum bicolor (L.) Moench) in dryland areas of Tanzania

Nutrient deficiency, high rate of evapotranspiration, and insufficient and erratic rainfall are the critical challenges for crop production in the dryland areas (DLAs) of Sub-Saharan Africa, including Tanzania, where 61% of arable land is prone to drought. In addressing these challenges, field trials were conducted in central Tanzania to evaluate the interactive effects of ripping and tie-ridges with organic (FYM) and inorganic fertilizers (N) on the mitigation of the critical period of soil moisture stress (CPSMS) for sorghum yield performance. Both in situ rainwater harvesting techniques (IRWHT) and flat-cultivated land were integrated with 8 Mg FYM ha^–1, 70 Kg N ha^–1, and a combination of 35 Kg N ha^–1 and 4 Mg FYM ha^–1 (N+ FYM). Among the IRWHT, tie-ridges stored a significant water volume of 577 and 457 m³ ha^–1, which mitigated the CPSMS by the maximum of 95% and 37% for the above-average rainfall and below-average rainfall season, respectively. However, it only registered the highest grain yield (2.02 Mg ha^–1) and biomass (3.46 Mg ha^–1) in a below-average rainfall season. The highest overall grain yield (5.73 Mg ha^–) and biomass (12.09 Mg ha^–1) were harvested in ripping with combined fertilizer treatments in an above-average rainfall season, while the lowest grain yield (0.5 Mg ha^–1) and biomass (1.2 Mg ha^–1) were registered in the flat-cultivation control in the below-average rainfall season. In the latter season, IRWHT increased the mitigation potential in the order; flat cultivation < ripping < tie-ridges; and sorghum yield, highly correlated with drought mitigation index. The results showed that sorghum grain yield and final biomass performance depend on the influence of IRWHT applied, rainfall amount, soil moisture level, integrated fertilizer, and length of the CPSMS. In the above-average rainfall seasons, fertilizers mask the influence of the IRWHT. The opposite is true in the below-average rainfall season. Although ripping_– N+ FYM resulted in the highest overall yield, the study recommends practicing tie-ridges integrated with N+ FYM due to regular occurrences of low and unreliable rainfall in the dryland areas.     

Identification of Minimum Data Set Under Balanced Fertilization for Sustainable Rice Production and Maintaining Soil Quality in Alluvial Soils of Eastern India

The scarcity of non-renewable fertilizers resources and the consequences of climate change can dramatically influence the food security of future generation. Introduction of high yielding varieties, intensive cropping sequence and increasing demand of food grains day-by-day, application of recommended dose of fertilizers could not fulfill our targets due to outdated fertilizers recommendations are yet in practice. It not only alters soil quality, nutrient balance, microbial and enzymatic ecology but also affected productivity and sustainability of rice in Gangetic alluvial soils of India. The effect of fertilizers application based on “fertilizing the soil versus fertilizing the crop” which insure real balance between the applied and available soil nutrient is urgently needed. Hence, the present study was conducted during three consecutive crop seasons (2010, 2011, and 2012) to assess the effect of imbalance and balance fertilization based on initial soil test values and targeted yields, and to determine the effect of farmyard manure (FYM) when superimposed with balanced fertilizers on identification of minimum data set for the development soil quality, nutrient acquisition, and grain yield of rice. The six fertilizer treatments were laid out in a randomized block design with three replications. The treatments were: T₁-control (no fertilization), T₂-farmyard manure @ 5 t ha^?1, T₃-farmers practice (60:30:30 kg N:P₂O₅:K₂O ha^?1), T₄-precise application of mineral fertilizers based on initial soil test values (77:24:46 kg N:P₂O₅:K₂O ha^?1) for targeted grain yield of 4.0 t ha^?1, T₅-precise application of mineral fertilizers based on initial soil test values (74:23:43 kg N:P₂O₅:K₂O ha^?1) plus FYM (5 t ha^?1) for targeted grain yield of 4.0 t ha^?1 and T₆-precise application of mineral fertilizers based on initial soil test values (135:34:65 kg N:P₂O₅:K₂O ha^?1) for targeted rice grain yield of 5.0 t ha^?1. Result revealed that the targeted rice grain yield of 4.0 and 5.0 t ha^?1 was achieved in T₄ and T₆ treatments with 1.59% (4.06 t ha^?1) and –3.40% (4.83 t ha^?1) deviations, respectively. T₄, T_5, and T₆ significantly increased crop growth, nutrient uptake, available P (P_a) and K (K_a) and augmented rice grain yield by 10.6, 20.2 and 31.6%, respectively, over T₃. Microbial biomass carbon, soil respiration and enzymatic activity were enhanced significantly in T₅ as compared to T₆. Highest soil quality index was found in T₅ (0.95) followed by T₆ (0.90) and, lowest was in T₁ (0.63). The contribution of minimum data set (MDS) toward the SQI was in the descending order of ALP (30.6%) > SOC (21.5%) > K_a (11.3%) > PSM (9.68%) > N_a (8.51%). Overall, rice yield and soil quality was improved by using balance fertilization based on fertilizing the crop Vs fertilizing the soil in alluvial soils of India.     

Effects of genotype on the response of Populus tremuloides michx. To ozone and nitrogen deposition

Elevated O₃ concentrations and N deposition levels co -occur in much of eastern United States. However, very little is known about their combined effects on tree growth. The effects of three O₃ treatments: charcoal-filtered air, non-filtered air and O₃, added at the rate of 80 ppb for 6 hr d^?1 3 d per week), four N deposition levels (0, 10, 20 and 40 kg ha^?1 yr^?1), and their interactions on growth of two Populus tremuloides clones in open-top chambers at two sites 600 km apart in Michigan were examined. Our results revealed a highly significant fertilization effect of the N treatments, even at the 10 kg ha^?1 yr^?1 rate. Ozone alone induced foliar injury, but not significant growth reductions. There was an indication that O₃ decreased growth at the O N level, but this decrease was reversed in all N treatments by the N fertilization effect. Further study is needed to more fully understand the combined effects of N deposition and O₃.     

Elevated atmospheric carbon dioxide effects on sorghum and soybean nutrient status 1

Increasing atmospheric carbon dioxide (CO₂) concentration could have significant implications on technologies for managing plant nutrition to sustain crop productivity in the future. Soybean (Glycine max [L.] Merr.) (C3 species) and grain sorghum (Sorghum bicolor [L.] Moench) (C4 species) were grown in a replicated split‐plot design using open‐top field chambers under ambient (357 μmol/mol) and elevated (705 μmol/mol) atmospheric CO₂. At anthesis, leaf disks were taken from upper mature leaves of soybean and from the third leaf below the head of sorghum for analysis of plant nutrients. Leaf greenness was measured with a Minolta SPAD‐502 chlorophyll meter. Concentrations of chlorophylls a and b and specific leaf weight were also measured. Above‐ground dry matter and seed yield were determined at maturiry. Seed yield of sorghum increased 17.5% and soybean seed yield increased 34.7% with elevated CO₂. There were no differences in extractable chlorophyll concentration or chlorophyll meter readings due to CO₂ treatment, but meter readings were reduced 6% when sorghum was grown in chambers as compared in the open. Leaf nitrogen (N) concentration of soybean decreased from 54.5 to 39.1 g/kg at the higher CO₂ concentration. Neither the chambers nor CO₂ had an effect on concentrations of other plant nutrients in either species. Further work under field conditions is needed to determine if current critical values for tissue N in crops, especially C3 crops, should be adjusted for future increases in atmospheric CO₂ concentration.     

Modeling of Interactive Effects of Rainfall,Evaporation, Soil Temperature,and Soil Fertility for Sustainable Productivity of Sorghum + Cowpea and Cotton + Black Gram Intercrops under Rotation Trials in a Rain-Fed Semi-arid Vertisol

Long-term effects of the different combinations of nutrient-management treatments were studied on crop yields of sorghum + cowpea in rotation with cotton + black gram. The effects of rainfall, soil temperature, and evaporation on the status of soil fertility and productivity of crops were also modeled and evaluated using a multivariate regression technique. The study was conducted on a permanent experimental site of rain-fed semi-arid Vertisol at the All-India Coordinated Research Project on Dryland Agriculture, Kovilpatti Centre, India, during 1995 to 2007 using 13 combinations of nutrient-management treatments. Application of 20 kg nitrogen (N) (urea) + 20 kg N [farmyard manure (FYM)] + 20 kg phosphorus (P) ha^?1 gave the greatest mean grain yield (2146 kg ha^?1) of sorghum and the fourth greatest mean yield (76 kg ha^?1) of cowpea under sorghum + cowpea system. The same treatment maintained the greatest mean yield of cotton (546 kg ha^?1) and black gram (236 kg ha^?1) under a cotton + cowpea system. When soil fertility was monitored, this treatment maintained the greatest mean soil organic carbon (4.4 g kg^?1), available soil P (10.9 kg ha^?1), and available soil potassium (K) (411 kg ha^?1), and the second greatest level of mean available soil N (135 kg ha^?1) after the 13-year study. The treatments differed significantly from each other in influencing soil organic carbon (C); available soil N, P, and K; and yield of crops attained under sorghum + cowpea and cotton + black gram rotations. Soil temperature at different soil depths at 07:20 h and rainfall had a significant influence on the status of soil organic C. Based on the prediction models developed between long-term yield and soil fertility variables, 20 kg N (urea) + 20 kg N (FYM) + 20 kg P ha^?1 could be prescribed for sorghum + cowpea, and 20 kg N (urea) + 20 kg N (FYM) could be prescribed for cotton + black gram. These combinations of treatments would provide a sustainable yield in the range of 1681 to 2146 kg ha^?1 of sorghum, 74 to 76 kg ha^?1 of cowpea, 486 to 546 kg ha^?1 of cotton, and 180 to 236 kg ha^?1 of black gram over the years. Beside assuring greater yields, these soil and nutrient management options would also help in maintaining maximum soil organic C of 3.8 to 4.4 g kg^?1 soil, available N of 126 to 135 kg ha^?1, available soil P of 8.9 to 10.9 kg ha^?1, and available soil K of 392 to 411 kg ha^?1 over the years. These prediction models for crop yields and fertility status can help us to understand the quantitative relationships between crop yields and nutrients status in soil. Because black gram is unsustainable, as an alternative, sorghum + cowpea could be rotated with cotton for attaining maximum productivity, assuring sustainability, and maintaining soil fertility on rain-fed semi-arid Vertisol soils.     

Effect of nitrogen fertilizer rate and timing on sorghum productivity in Ethiopian highland Vertisols

Sorghum is cultivated on Vertisols in the Ethiopian Highlands. An experiment was conducted in the Gumara-Maksegnit watershed in 2013 and 2014 to assess the effect of rate and timing of nitrogen fertilizer application on the possibility to shorten the maturity period and to improve the productivity of sorghum. The experiment was laid out as Randomized Complete Block Design with three replications. Treatments were nitrogen doses between 0 and 87 kg N ha^?1 as urea applied at planting, at knee-height stage or in split doses at both stages. Results showed that application of 23, 41, 64 and 87 kg ha^?1 N gave a yield increase of 40, 53, 62 and 69% over the control (0 kg N ha^?1), respectively. In addition, split application of 41 kg ha^?1, 64 kg ha^?1 and 87 kg ha^?1 of nitrogen fertilizer, half at planting and half at knee height stage, gave 19%, 15% and 18% increase in sorghum grain yield over a single dose application, respectively. Applying 87 kg ha^?1 nitrogen fertilizer with split application half at planting and half at knee height stage, along with 46 kg ha^?1 of P₂O_5, gave the highest grain yield and income.     

Understanding the response of sorghum cultivars to nitrogen applications in the semi-arid Nigeria using the agricultural production systems simulator

Abstract

The Agricultural Production Systems simulator (APSIM) model was calibrated and evaluated using two improved sorghum varieties conducted in an experiment designed in a randomized complete block, 2014–2016 at two research stations in Nigeria. The results show that the model replicated the observed yield accounting for yield differences and variations in phenological development between the two sorghum cultivars. For early-maturing cultivar (ICSV-400), the model indicated by low accuracy with root means square error (RMSE) for biomass and grain yields of 20.3% and 23.7%. Meanwhile, Improved-Deko (medium-maturing) cultivar shows the model was calibrated with low RMSE (11.1% for biomass and 13.9% for grain). Also, the model captured yield response to varying Nitrogen (N) fertilizer applications in the three agroecological zones simulated. The N-fertilizer increased simulated grain yield by 26–52% for ICSV-400 and 19–50% for Improved-Deko compared to unfertilized treatment in Sudano-Sahelian zone. The insignificant yield differences between N-fertilizer rates of 60 and 100 kgha^?1 suggests 60 kgNha^?1 as the optimal rate for Sudano-Sahelian zone. Similarly, grain yield increased by 23–57% for ICSV-400 and 19–59% for Improved Deko compared to unfertilized N-treatment while the optimal mean grain yield was simulated at 80 kgNha^?1 in the Sudan savanna zone. In the northern Guinea savanna, mean simulated grain yield increased by 8–20% for ICSV-400 and 12–23% for Improved-Deko when N-fertilizer was applied compared to unfertilized treatment. Optimum grain yield was obtained at 40 kgha^?1. Our study suggests a review of blanket recommended fertilizer rates across semi-arid environments for sorghum to maximize productivity and eliminate fertilizer losses, means of adaptation strategies to climate variability.     

Effect of 13 Years Long Minimum Tillage Cum Conjunctive Nutrient Management Practices on Soil Fertility and Nitrogen Chemical Fractions under Sorghum (Sorghum bicolour (L.) Moench)–Mungbean (Vigna radiata (L.) Wilczek) System in Semi-Arid Tropical Alfisol (SAT) in Southern India

A long-term experiment was conducted at the Central Research Institute for Dryland Agriculture for 13 years to evaluate the effect of low tillage cum cheaper conjunctive nutrient management practices in terms of productivity, soil fertility, and nitrogen chemical pools of soil under sorghum–mung bean system in Alfisol soils. The results of the study clearly revealed that sorghum and mung bean grain yield as influenced by low tillage and conjunctive nutrient management practices varied from 764 to 1792 and 603 to 1008 kg ha^?1 with an average yield of 1458 and 805 kg ha^?1 over a period of 13 years, respectively. Of the tillage practices, conventional tillage (CT) maintained 11.0% higher yields (1534 kg ha^?1) over the minimum tillage (MT) (1382 kg ha^?1) practice. Among the conjunctive nutrient management treatments, the application of 2 t Gliricidia loppings + 20 kg nitrogen (N) through urea to sorghum crop recorded significantly highest grain yield of 1712 kg ha^?1 followed by application of 4 t compost + 20 kg N through urea (1650 kg ha^?1) as well as 40 kg N through urea alone (1594 kg ha^?1). Similar to sorghum, in case of mung bean also, CT exhibited a significant influence on mung bean grain yields (888 kg ha^?1) which was 6.7% higher compared to MT (832 kg ha^?1). Among all the conjunctive nutrient management treatments, 2 t compost + 10 kg N through urea and 2 t compost + 1 t Gliricidia loppings performed significantly well and recorded similar mung bean grain yields of 960 kg ha^?1 followed by 1 t Gliricidia loppings + 10 kg N through urea (930 kg ha^?1). The soil nitrogen chemical fractions (SNCFs) were also found to be significantly influenced by tillage and conjunctive nutrient management treatments. Further, a significant correlation of SNCF with total soil nitrogen was observed. In the correlation study, it was also observed that N fraction dynamically played an important role in enhancing the availability pool of N in soil and significantly influenced the yield of sorghum grain and mung bean.     

Impacts of Ambient Ozone and/or Acid Mist on the Growth of 14 Tree Species: An Open-Top Chamber Study Conducted in Japan

Young trees of 14 species were exposed to ambient ozone (O₃), (charcoal-filtered air [CF] or non-filtered air [NF]) and/or acid mist (pH 5 or 3: SO₄ ^2?, NO₃ ^?, Cl^? at equivalent 1:2:1 ratio) over three seasons (from June 1993 to November 1995) using tunnel-type open-top chambers at two sites (Abiko: 25 m a.s.l. and Akagi: 540 m a.s.l.) in Japan. Ambient, 12-hr (0600–1800) mean O₃ concentration for April–September during the period of experiment at Akagi (41 ppb) was 40 % higher than that at Abiko (30 ppb). The NF- and CF-chambers had 90 % and 30 % of ambient O₃, respectively. Significant decreases in biomass in the NF treatments were observed in Pinus densiflora, Larix k aempferi, Picea abies, Abies firma, Abies homolepis, Abies veitchii, Cryptomeria japonica, Populus maximowiczii, Betula platyphylla, Fagus crenata and Zelkova serrata as compared with the CF treatment. These results indicate that the current ambient level of O₃ in Japan is high enough to have adverse effects on the growth of all tree species examined, except Pinus thunbergii, Chamaecyparis obtusa and Quercus mongolica. Increasing acidity of mist caused no growth decreases in all tree species examined. However, the growth decreases by O₃ were greater at pH 3 mist treatment than at pH 5 mist treatment on Abies veitchii and Fagus. This suggested that the O₃ effect on tree growth can be exacerbated by the deposition of acid mist, possibly associated with nitrate.     

Field Data of Hydrogen Peroxide Concentrations in Urban and Mountain Air in Southwestern Poland

The concentrations of ambient gas-phase hydrogen peroxide were measured during the summer of 1998, 1999 and 2000. The experiments were performed in the city of Wroclaw and in the vicinity of Mount Szrenica, 1362 m a.s.l., Poland. Analysis was carried out by the chemiluminescence method. Typical mean ranges of 30 min H₂O₂ concentrations measured were 1.4–6.0 μg m^-3 at Mount Szrenica, whereas in the urban atmosphere H₂O₂ concentrations were in the range of 2.7–11.7 μg m^-3. In the case of the urban atmosphere, H₂O₂ concentrations were well correlated only with solar radiation and temperature. In the mountain air, H₂O₂ concentrations increased along with the increase of temperature, O₃, CO and the decrease of humidity. The diurnal variation was not only caused by photochemicalprocesses.     

Growth response of Suaeda salsa (L.) Pall to graded NaCl concentrations and the role of chlorine in growth stimulation

Abstract

Growth response of a halophyte species, Suaeda salsa (L.) Pall, to graded NaCl concentrations was examined under water culture conditions. Growth increased with increasing NaCl concentration from 2 to 200 mol m^?3, but decreased at NaCl concentrations above 200 mol m^?3. Maximum growth was attained at 50 to 200 mol m^?3. The role of Na and Cl in the growth stimulation by NaCl was examined by growing S. salsa in nutrient solutions with or without Na and Cl separately at 5 and 50 mol m^?3. The growth stimulation induced by Cl was greater than that induced by Na, and Na did not significantly induce growth stimulation. The effect of Na or Cl on O₂ evolution from leaves was examined under 5 and 50 mol m^?3 concentrations using an oxygen electrode. Oxygen evolution from leaves in –Cl treatments was smaller than that in +Cl treatments both at 5 and 50 mol m^?3. The O₂ evolution in Na treatments with Cl was similar to that at NaCl. These results indicated that the mechanism of growth stimulation induced by Cl was mainly an increased photosystem II of photosynthesis in leaves. The contribution of Na on the growth stimulation of S. salsa by NaCl was smaller than Cl.     

Effect of Organic Residues with Varied Carbon–Nitrogen Ratios on Grain Yield,Soil Health,and Nitrous Oxide Emission from a Rice Agroecosystem

Experiments were conducted in an attempt to study the impact of using different organic residues as fertilizers on grain yield, magnitude of nitrous oxide (N₂O) emissions, and soil characteristics. Five fertilizer treatments including conventional nitrogen (N) fertilizer, cow manure, rice straw, poultry manure, and sugarcane bagasse were applied in the rice field in 2012. The maximum reduction in seasonal N₂O emissions (10–27%) was observed under the influence of rice straw application over conventional N fertilizer. The experiment was repeated for a second season in 2013 with the same treatments for further confirmation of the results obtained during the first year of experimentation. The application of rice straw also showed a slight advantage by increasing grain yield (4.38 t ha^?1) compared to control. Important soil properties and plant growth parameters were studied and their relationships with N₂O emission were worked out. The incorporation of organic residues helped in restoring and improving the soil health and effectively enhancing grain yield with reduced N₂O emission from rice fields.     

Tolerance of seven tropical pasture grasses to excess manganese

Abstract

Setaria and paspalum were found to be very tolerant of excess Mn. Green panic and sorghum were somewhat less tolerant with foliar symptoms due to excess Mn being exhibited in plants containing 1000 ppm Mn and yield reductions occurring in plants containing Mn concentrations of the order of 2000 ppm. Excess Mn did not effect the early seedling growth of sabi grass but regrowth was severely depressed. Rhodes grass and buffel grass were severely effected by excess manganese. Regrowth of these two species was more adversely effected than initial seedling growth indicating that these species probably would not survive to maintain a stable pasture in Mn toxic situations.

Accumulation of excess Mn was accompanied by a linear decline in Ca concentrations in all species.     

Effects of Nitrogen Management on Soil Nitrogen Content and Rice Grain Yield in Double Cropping Rice Production Area with Continuous Full Amount of Straw Returning

ABSTRACT

In order to formulate a nitrogen (N) management strategy under continuous full amount of straw returning (CFSR) for double cropping rice production, long-term (2013–2016) paddy field experiments were conducted in double cropping rice production area in the Jiangxi province, China. Five N fertilizer treatments under CFSR were tested, that is, (i) no N fertilizer application (CK); (ii) conventional N fertilizer application (165kg N ha^?1 and 195 kg N ha^?1 in early and late rice variety with the ratio of basal dressing to topdressing as 6:4, respectively) (CNF_6:4); (iii) recommended N fertilizer application (135 kg ha^?1 N and 165 kg ha^?1 N in early and late rice variety with the ratio of basal dressing to topdressing as 4:6, 6:4, and 8:2, respectively) (RNF_4:6, RNF_6:4, and RNF_8:2). Nitrogen fertilizer treatments under CFSR had 5.70% and 8.93% higher soil total nitrogen (TN), 1.32% and 0.80% higher available nitrogen (AN), 16.55% and 22.94% higher NH₄⁺-N, and 13.10% and 7.93% higher NO₃^--N than CK treatments in early and late rice variety, respectively. There were no differences in soil TN, AN, NH₄⁺-N, and NO₃^--N contents between CNF6:4 and RNF6:4 treatments, while CNF6:4 treatment showed higher or significantly higher soil N contents than RNF4:6 and RNF8:2 treatments. N fertilizer treatment under CFSR showed 88.9% and 43.20% higher grain yield and 62.15% and 42.52% higher panicle numbers than CK treatments in early and late rice variety, respectively. Compared with CNF6:4, RNF treatments did not significantly reduce grain yield and yield components in early and late rice variety, respectively, except for RNF8:2. Compared with RNF6:4 and 8:2, RNF4:6 showed higher rice grain yield, while no obvious differences in yield components were obtained among all RNF treatments. We concluded that N fertilizer under CFSR was helpful to improve soil N contents and double rice grain yield and panicle numbers. Appropriate reduction of N application (18% and 15% reduction in early and late rice variety, respectively) on the basis of adjusting ratio of basal dressing to topdressing as 4:6 and 6:4 did not significantly reduce soil TN and double rice grain yield and yield components, especially, the 40% basal N dressing and 60% N topdressing was beneficial to increase double rice grain yield under CFSR.