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Soil and crop management practices may influence biomass growth and yields of cotton (Gossypium hirsutum L.) and sorghum (Sorghum bicolorL.) and sequester significant amount of atmospheric CO2in plant biomass and underlying soil, thereby helping to mitigate the undesirable effects of global warming. This study examined the effects of three tillage practices [no-till (NT), strip till (ST), and chisel till (CT)], four cover crops [legume (hairy vetch) (Vicia villosa roth), nonlegume (rye) (Secale cerealeL), hairy vetch/rye mixture, and winter weeds orno covercrop], and three N fertilization rates (0, 60-65, and 120-130 kg N ha -1) on the amount of C sequestered in cotton lint (lint + seed), sorghum grain, their stalks (stems + leaves) and roots, and underlying soil from 2000 to 2002 in central Georgia, USA. A field experiment was conducted on a Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Kandiudults). In 2000, C accumulation in cotton lint was greater in NT with rye or vetch/rye mixture but in stalks, it was greater in ST with vetch or vetch/rye mixture than in CT with or without cover crops. Similarly, C accumulation in lint was greater in NT with 60 kg N ha -1 but in stalks, it was greater in ST with 60 and 120 kg N ha -1 than in CT with 0 kg N ha -1. In 2001, C accumulation in sorghum grains and stalks was greater in vetch and vetch/rye mixture with or without N rate than in rye without N rate. In 2002, C accumulation in cotton lint was greater in CT with or without N rate but in stalks, it was greater in ST with 60 and 120 kg N ha -1 than in NT with or without N rate. Total C accumulation in the above- and belowground biomass in cotton ranged from 1.7 to 5.6 Mg ha -1 and in sorghum ranged from 3.4 to 7.2 Mg ha -1. Carbon accumulation in cotton and sorghum roots ranged from 1 to 14% of the total C accumulation in above- and belowground biomass. In NT, soil organic C at 0-10 cm depth was greater in vetch with 0 kg N ha -1 or in vetch/rye with 120-130 kg N ha -1 than in weeds with 0 and 60 kg N ha -1 but at 10-30 cm, it was greater in rye with 120-130 kg N ha -1 than in weeds with or without rate. In ST, soil organic C at 0-10 cm was greater in rye with 120-130 kg N ha -1 than in rye, vetch, vetch/rye and weeds with 0 and 60 kg N ha-1. Soil organic C at 0-10 and 10-30 cm was also greater in NT and ST than in CT. Since 5 to 24% of C accumulation in lint and grain were harvested, C sequestered in cotton and sorghum stalks and roots can be significant in the terrestrial ecosystem and can significantly increase C storage in the soil if these residues are left after lint or grain harvest, thereby helping to mitigate the effects of global warming. Conservation tillage, such as ST, with hairy vetch/rye mixture cover crops and 60-65 kg N ha -1 can sustain C accumulation in cotton lint and sorghum grain and increase C storage in the surface soil due to increased C input from crop residues and their reduced incorporation into the soil compared with conventional tillage, such as CT, with no cover crop and N fertilization, thereby maintaining crop yields, improving soil quality, and reducing erosion.

Management practices may influence cotton (Gossypium hirsutum L.) and sorghum Sorghum bicolor (L.) Moench) root C and N inputs for improving soil quality. We examined the influence of three tillage practices no-till (NT), strip till (ST), and chisel till (CT), four cover crops (legume hairy vetch (Vicia villosa Roth), nonlegume rye (Secale cereale L.), biculture of legume and nonlegume (vetch and rye), and no cover crops (winter weeds)), and three N fertilization rates (0, 60-65, and 120-130 kg N ha(-1)) on cotton and sorghum root C and N from the 0- to 120-cm soil depth. A field experiment was conducted in a Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Kandiudults) from 2000 to 2002 in central Georgia. Root C and N at 0 to 15 cm were greater in NT than in ST and CT in 2000 cotton and 2001 sorghum, but at 30 to 60 cm they were greater in ST than in NT and CT in 2000 cotton. Root C and N at 0 to 15 cm were also greater with vetch and rye biculture than with vetch and weeds in 2001 sorghum. Total root C and N at 0 to 120 cm were greater in ST with vetch than in ST with rye or in CT with weeds in 2000 cotton. In contrast, total root N was greater in NT with rye than in ST with rye or CT with vetch in 2001 sorghum and 2002 cotton. Total root N was also greater in CT with 60 kg N ha(-1) than in NT or CT with 120 kg N ha(-1) in 2000 cotton, but was greater in ST with 60 kg N ha(-1) than in NT with 0 kg N ha(-1) or CT with 120 kg N ha(-1) in 2002 cotton. The NT or ST with vetch and rye cover crops and 60 kg N ha(-1) may increase cotton and sorghum root C and N compared with CT with no cover crops and N fertilization, thereby helping to improve soil quality and productivity.

Biculture legume-cereal cover cropping may enhance above- and belowground biomass yields and C and N contents. The increase in C and N supply to the soil has the potential to improve soil quality and crop productivity compared with monoculture cover crop species. We examined above- and belowground (0- to 120-cm soil depth) biomass yields and C and N contents of a legume hairy vetch (Vicia villosa Roth), nonlegume rye (Secale cereale L.), and biculture of legume and nonlegume (vetch and rye) cover crops planted without tillage in the fall of 1999 to 2001 in central Georgia. After cover crop kill in the spring, cotton (Gossypium hitsutum L.) and sorghum Sorghum bicolor (L.) Moench) were planted using three tillage practices (no-till, strip till, and chisel till) with three N fertilization rates (0, 60 to 65, and 120 to 130 kg N ha(-1)). The field experiment was arranged in a split-split plot treatment with three replications on a Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Kandiudults). Aboveground biomass yield of rye decreased from 6.1 to 2.3 Mg ha(-1) from 2000 to 2002, but yield of hairy vetch varied (2.4 to 5.2 Mg ha(-1)). In contrast, biomass yield of vetch and rye biculture (5.6 to 8.2 Mg ha(-1)) was greater than that of rye and vetch planted alone in all years. Compared with winter weeds in no cover crop treatment, C content in rye (1729 to 2670 kg ha(-1)) was greater due to higher biomass yield, but N content in vetch (76 to 165 kg ha(-1)) was greater due to higher N concentration, except in 2002. As a result, C (2260 to 3512 kg ha(-1)) and N (84 to 310 kg ha(-1)) contents in biculture were greater than those from monocultures in all years. Similarly, belowground biomass yield and C and N contents were greater in biculture than in monocultures. In 2001, aboveground biomass yield and C and N contents in cover crops were also greater in strip till with biculture than in other treatments, except in chisel till with vetch and biculture, but belowground biomass yield and N content were greater in chisel till with biculture than in no-till, strip till, and chisel till with weeds. Cotton lint yield was lower with biculture than with rye, but sorghum grain yield and cotton and sorghum biomass (stems + leaves) yields and N uptake were greater with biculture than with rye. Because of higher biomass yield and C and N contents, biculture of hairy vetch and rye cover crops may increase N supply, summer crop yields, and N uptake compared with rye and may increase potentials to improve soil organic matter and reduce N leaching compared with vetch.

Soil carbon (C) sequestration in tilled and nontilled areas can be influenced by crop management practices due to differences in plant C inputs and their rate of mineralization. We examined the influence of four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secale cereale L.)], biculture of legume and nonlegume (vetch and rye), and no cover crops (or winter weeds)} and three nitrogen (N) fertilization rates (0, 60 to 65, and 120 to 130 kg N ha-1) on C inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)], and soil organic carbon (SOC) at the 0- to 120-cm depth in tilled and nontilled areas. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic Plinthic Paleudults) from 1999 to 2002 in central Georgia. Total C inputs to the soil from cover crops, cotton, and sorghum from 2000 to 2002 ranged from 6.8 to 22.8 Mg ha-1. The SOC at 0 to 10 cm fluctuated with C input from October 1999 to November 2002 and was greater from cover crops than from weeds in no-tilled plots. In contrast, SOC values at 10 to 30 cm in no-tilled and at 0 to 60 cm in chisel-tilled plots were greater for biculture than for weeds. As a result, C at 0 to 30 cm was sequestered at rates of 267, 33, -133, and -967 kg C ha-1 yr-1 for biculture, rye, vetch, and weeds, respectively, in the no-tilled plot. In strip-tilled and chisel-tilled plots, SOC at 0 to 30 cm decreased at rates of 233 to 1233 kg C ha-1 yr-1. The SOC at 0 to 30 cm increased more in cover crops with 120 to 130 kg N ha-1 yr-1 than in weeds with 0 kg N ha-1 yr-1, regardless of tillage. In the subtropical humid region of the southeastern United States, cover crops and N fertilization can increase the amount of C input and storage in tilled and nontilled soils, and hairy vetch and rye biculture was more effective in sequestering C than monocultures or no cover crop.

Received for publication June 13, 2006. Management practices may influence soil N levels due to crop uptake and leaching. We evaluated the effects of three tillage practices [no-till (NT), strip till (ST), and chisel till (CT)], four cover crops [hairy vetch (Vicia villosa Roth), rye (Secale cereale L.), vetch + rye biculture, and winter weeds or no cover crop], and three N fertilization rates (0, 60-65, and 120-130 kg N ha-1) on NH4-N and NO3-N contents in Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Paleudults), and N uptake by cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench] from 2000 to 2002 in central Georgia. Nitrogen content was higher in vetch and vetch + rye than in rye and weeds. Soil NH4-N content at 0 to 30 cm was higher at harvest than at planting, and higher in NT or vetch with 120 to 130 kg N ha-1 than with other treatments. The NO3-N content at 0 to 120 cm varied with date of sampling and was higher with vetch than with rye and weeds. The NO3-N content at 0 to 10 cm was higher in CT with vetch than in NT and ST with rye or weeds. From November 2000 to April 2001 and from November 2001 to April 2002, N loss from crop residue and soil at 0 to 120 cm was higher with vetch than with other cover crops. Nitrogen removed by cotton lint was higher with rye than with other cover crops in 2000 and higher with 0 and 60 than with 120 kg N ha-1 in 2002, but N removed by sorghum grain and cotton and sorghum biomass were higher with vetch than with rye, and higher with 120 to 130 than with 0 kg N ha-1. Because of higher N supply, vetch increased soil mineral N and cotton and sorghum N uptake compared with rye, but also increased the potential for N leaching. The potential for N leaching can be reduced and crop N uptake can be optimized by mixing vetch with rye.

Background Urothelial bladder cancer (UBC) accounts for 10,000 new diagnoses and 5000 deaths annually in the UK (Cancer Research UK, http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bladder-cancer , Cancer Research UK, Accessed 26 Mar 2018). Cisplatin-based chemotherapy is standard of care therapy for UBC for both palliative first-line treatment of advanced/metastatic disease and radical neoadjuvant treatment of localised muscle invasive bladder cancer. However, cisplatin resistance remains a critical cause of treatment failure and a barrier to therapeutic advance in UBC. Based on supportive pre-clinical data, we hypothesised that DNA methyltransferase inhibition would circumvent cisplatin resistance in UBC and potentially other cancers. Methods The addition of SGI-110 (guadecitabine, a DNA methyltransferase inhibitor) to conventional doublet therapy of gemcitabine and cisplatin (GC) is being tested within the phase Ib/IIa SPIRE clinical trial. SPIRE incorporates an initial, modified rolling six-dose escalation phase Ib design of up to 36 patients with advanced solid tumours followed by a 20-patient open-label randomised controlled dose expansion phase IIa component as neoadjuvant treatment for UBC. Patients are being recruited from UK secondary care sites. The dose escalation phase will determine a recommended phase II dose (RP2D, primary endpoint) of SGI-110, by subcutaneous injection, on days 1–5 for combination with GC at conventional doses (cisplatin 70 mg/m 2 , IV infusion, day 8; gemcitabine 1000 mg/m 2 , IV infusion, days 8 and 15) in every 21-day cycle. In the dose expansion phase, patients will be randomised 1:1 to GC with or without SGI-110 at the proposed RP2D. Secondary endpoints will include toxicity profiles, SGI-110 pharmacokinetics and pharmacodynamic biomarkers, and pathological complete response rates in the dose expansion phase. Analyses will not be powered for formal statistical comparisons and descriptive statistics will be used to describe rates of toxicity, efficacy and translational endpoints by treatment arm. Discussion SPIRE will provide evidence for whether SGI-110 in combination with GC chemotherapy is safe and biologically effective prior to future phase II/III trials as a neoadjuvant therapy for UBC and potentially in other cancers treated with GC. Trial Registration EudraCT Number: 2015–004062-29 (entered Dec 7, 2015) ISRCTN registry number: 16332228 (registered on Feb 3, 2016)