Using zero tillage, fertilisers and legume rotations to maintain productivity and soil fertility in opportunity cropping systems on a shallow Vertosol

The effect of 2 tillage practices (zero v. conventional), fertiliser application (nitrogen, phosphorus and zinc), and pulse–cereal rotation on changes in soil mineral nitrogen, plant-available water in the soil, grain yield and protein, and key soil fertility parameters (total nitrogen, organic carbon) in the Central Highlands of Queensland were examined between 1991 and 1998. Four pasture treatments (perennial legume, perennial grass, annual legume and legume–grass mixes) were included in January 1995, following previously unsuccessful attempts to grow lucerne and annual medics. The experiment was conducted as an opportunity cropping system on an open downs soil at Gindie that is representative of a large proportion (70%) of soils in the Central Highlands. Tillage practice did not affect the amount of mineral nitrate or the plant-available water content of the soil at planting, except in 1991 and 1998 when plant-available water content was higher under conventional tillage than zero tillage. However, zero tillage improved grain yield in 2 of 4 years (wheat in 1992; sorghum in 1996), increased uptake of nitrogen in every crop and produced greater grain protein levels in both wheat crops grown than conventional tillage. There were grain responses to nitrogen + phosphorus fertilisers (wheat in 1991 and sorghum in 1997). Grain protein was increased with applications of nitrogen regardless of whether phosphorus was added in 3 of the 4 crops planted. Sowing a pulse did not significantly increase grain yields in the following crop although it did increase soil mineral nitrogen at planting. Soil nitrate remained low in control (P0N0) plots (<39 kg N/ha) when crops were planted each year but increased significantly (average 84 kg N/ha) following a long fallow of 3.5 years resulting from drought. Plant-available water content of the soil at sowing was lower where chickpeas had been grown the previous season than with wheat. Neither tillage practice nor fertiliser application affected soil organic carbon or soil total nitrogen concentrations in the topsoil. However, all pasture treatments improved soil total nitrogen compared with continuous cropping, and with the exception of annual pasture legumes, also improved soil organic carbon after only 2 seasons. Largest improvements in soil fertility (total nitrogen and organic carbon) occurred with perennial species. It was concluded that zero tillage practices can have beneficial impacts on grain yields as well as minimising environmental degradation such as soil erosion in this region. However, if soil fertility levels are to be maintained, or improved, perennial pasture rotations will need to be used as current levels of fertiliser application or rotations with pulses had no significant beneficial effect

Using zero tillage, fertilisers and legume rotations to maintain productivity and soil fertility in opportunity cropping systems on a shallow Vertosol

The effect of 2 tillage practices (zero v. conventional), fertiliser application (nitrogen, phosphorus and zinc), and pulse–cereal rotation on changes in soil mineral nitrogen, plant-available water in the soil, grain yield and protein, and key soil fertility parameters (total nitrogen, organic carbon) in the Central Highlands of Queensland were examined between 1991 and 1998. Four pasture treatments (perennial legume, perennial grass, annual legume and legume–grass mixes) were included in January 1995, following previously unsuccessful attempts to grow lucerne and annual medics. The experiment was conducted as an opportunity cropping system on an open downs soil at Gindie that is representative of a large proportion (70%) of soils in the Central Highlands. Tillage practice did not affect the amount of mineral nitrate or the plant-available water content of the soil at planting, except in 1991 and 1998 when plant-available water content was higher under conventional tillage than zero tillage. However, zero tillage improved grain yield in 2 of 4 years (wheat in 1992; sorghum in 1996), increased uptake of nitrogen in every crop and produced greater grain protein levels in both wheat crops grown than conventional tillage. There were grain responses to nitrogen + phosphorus fertilisers (wheat in 1991 and sorghum in 1997). Grain protein was increased with applications of nitrogen regardless of whether phosphorus was added in 3 of the 4 crops planted. Sowing a pulse did not significantly increase grain yields in the following crop although it did increase soil mineral nitrogen at planting. Soil nitrate remained low in control (P0N0) plots (<39 kg N/ha) when crops were planted each year but increased significantly (average 84 kg N/ha) following a long fallow of 3.5 years resulting from drought. Plant-available water content of the soil at sowing was lower where chickpeas had been grown the previous season than with wheat. Neither tillage practice nor fertiliser application affected soil organic carbon or soil total nitrogen concentrations in the topsoil. However, all pasture treatments improved soil total nitrogen compared with continuous cropping, and with the exception of annual pasture legumes, also improved soil organic carbon after only 2 seasons. Largest improvements in soil fertility (total nitrogen and organic carbon) occurred with perennial species. It was concluded that zero tillage practices can have beneficial impacts on grain yields as well as minimising environmental degradation such as soil erosion in this region. However, if soil fertility levels are to be maintained, or improved, perennial pasture rotations will need to be used as current levels of fertiliser application or rotations with pulses had no significant beneficial effect

Changes in soil chemical and physical properties following legumes and opportunity cropping on a cracking clay soil

Incorporating legumes into the cropping system has been shown to significantly improve the nitrogen nutrition of cereal crops in Central Queensland. However, little is known about the effect of these legumes on the chemical and physical properties of soil. We examined changes in soil chemical (total nitrogen, organic carbon and pH) and physical (bulk density, cone penetrometer resistance and saturated hydraulic conductivity) properties following either continuous cropping (sorghum or mungbean) or pasture legumes (siratro, lucerne, lablab and desmanthus) over 4 years. Soil carbon was also fractionated using a KMnO4 oxidation procedure which classifies the soil carbon into either labile or non-labile pools. All pasture legumes except desmanthus increased soil total nitrogen in the topsoil (0–10 cm) after only 2 years compared with sorghum. Total nitrogen in the soil did not significantly change under mungbean. Soil organic carbon progressively increased under siratro, desmanthus and sorghum but remained unchanged under the other legumes. Before the experiment, the percentage of total soil carbon classified as labile (oxidised by 333 mmol KMnO4/L) ranged from 14 to 17%. The amount of labile carbon increased by 17% after 3 years of siratro, remained unchanged under desmanthus and sorghum, and decreased under the annual legumes and lucerne. Non-labile carbon remained either unchanged or increased under all legumes, whereas it tended to decrease after 3 consecutive sorghum crops. Soil pH was generally highest under sorghum and lowest under lablab. Soil after sorghum had higher bulk density and penetrometer resistance compared with the effect of legumes but these differences were comparatively small. Saturated hydraulic conductivity of the soil was much higher on the soil surface than at 10 cm. On the surface, soil hydraulic conductivity (saturated) values were generally lower following siratro and higher after sorghum than the other species. At 10 cm depth, soil hydraulic conductivity (saturated) was generally lower in sorghum and, to a lesser extent, in mungbean plots reflecting the significantly lower density of macropores under these crops. It was concluded that although all legumes generally enhanced the chemical and physical properties of the cracking clay, perennial legumes such as siratro would have a greater beneficial effect in the longer term than annual legumes

Legume and opportunity cropping systems in central Queensland. 1. Legume growth, nitrogen fixation, and water use

An experiment, established on a cracking clay (Vertisol) at Emerald, central Queensland, studied the dry matter (DM) production, nitrogen (N) fixation, and water use of several potential ley-legume species over 4 seasons (1994–1997). Four ley legumes (siratro, Macroptilium atropurpureum cv. Siratro; lucerne, Medicago sativa cv. Trifecta; lablab, Lablab purpureus cv. Highworth; and desmanthus, Desmanthus virgatus cv. Marc) were compared with a pulse (mungbean, Vigna radiata cv. Satin), and grain sorghum (Sorghum bicolor) was included as a non-legume control. Overall, the annual legumes lablab (17.5 t/ha) and mungbean (13.4 t/ha) and the perennial siratro (16.2 t/ha) accumulated more DM than the perennials lucerne (9.6 t/ha) and desmanthus (7.1 t/ha). Lucerne produced little DM in its first year, but in later years had similar production to siratro and lablab. Desmanthus produced >4 t/ha of DM in the first year but barely survived during later seasons. Annual legumes grew faster and exhausted soil water more rapidly than the perennials. The perennials were able to extract more water from the soil than the annual legumes and sorghum, but were inefficient at converting small to moderate rainfall events (25–50 mm) into DM production. During the fallow following the growth of lablab and mungbean, nitrate-N in soil increased and was always greater at the time of re-sowing than for the perennial legumes and sorghum. Initially, the 2 annual legumes derived a high proportion (50% to >70%) of their above-ground N from fixation (%Ndfa) but this declined as the experiment progressed to low values (90% for lucerne, and remained high (25–50%) throughout the experiment. N fixation rates were strongly negatively correlated with soil nitrate. Over the 4 years, siratro fixed 161 kg N/ha, lucerne 120, lablab 119, mungbean 78, and desmanthus 19 based on above-ground biomass. Mungbean had a net negative N balance (–80 kg N/ha) due to N exported in grain

Legume and opportunity cropping systems in central Queensland. 2. Effect of legumes on following crops

Poor yields and low grain protein in cereal crops resulting from declining soil fertility, especially nitrogen (N), are major threats to the grains industry in central Queensland. The effect of 4 different pasture-ley legumes [siratro (Macroptilium atropurpureum cv. Siratro), lucerne (Medicago sativa cv. Trifecta), lablab (Lablab purpureus cv. Highworth), and desmanthus (Desmanthus virgatus cv. Marc)] on grain yield and quality of sorghum crops was compared with that of a pulse (mungbean; Vigna radiata cv. Satin) or continuous cropping with grain sorghum (Sorghum bicolor). Legume leys consistently resulted in large increases in grain yield (188–272%), N uptake by sorghum (145–345%), and grain protein (0.21–7.0% increase in grain protein) in sorghum test-crops compared with continuous sorghum crops to which no fertiliser N had been added. The positive effect of legumes persisted up to 3 sorghum test-crops after only 1 year of legumes, although by the third year the effect was comparatively small. Mungbean and lablab generally produced the largest benefit in sorghum test-crops in the first year after legumes, whereas desmanthus and lucerne produced the least benefit. Adding fertiliser N (up to 75 kg N/ha) significantly improved grain yields and N uptake of sorghum test-crops in 3 of 4 years. However, responses to fertilisers were less than those resulting from legumes, which was ascribed to increased availability of legume N to sorghum. Legumes progressively increased soil nitrate in all subsequent sorghum test-crops (compared with continuous sorghum crops), rising from 6.8–18.9 kg NO3-N/ha after 1 year of legumes to 24.2–59.6 kg NO3-N/ha after 3 years of legumes. There was little difference between the legumes in their ability to increase soil nitrate, with the exception of desmanthus, which consistently resulted in the lowest amount of soil nitrate for subsequent test-crops and lowest uptake of N by these crops. Plant-available water content (PAWC) at planting of the sorghum test-crop was only significantly (P<0.05) affected by previous species in 1997, when it was lowest in plots previously sown to siratro and lucerne and highest in sorghum and mungbean plots. In both 1996 and 1997, plots sown to sorghum had significantly higher PAWC at anthesis and grain maturity when previous plots were sorghum rather than legumes

Mutations in GDF11 and the extracellular antagonist, Follistatin, as a likely cause of Mendelian forms of orofacial clefting in humans

Contains fulltext : 208676.pdf (publisher's version ) (Closed access)Cleft lip with or without cleft palate (CL/P) is generally viewed as a complex trait with multiple genetic and environmental contributions. In 70% of cases, CL/P presents as an isolated feature and/or deemed nonsyndromic. In the remaining 30%, CL/P is associated with multisystem phenotypes or clinically recognizable syndromes, many with a monogenic basis. Here we report the identification, via exome sequencing, of likely pathogenic variants in two genes that encode interacting proteins previously only linked to orofacial clefting in mouse models. A variant in GDF11 (encoding growth differentiation factor 11), predicting a p.(Arg298Gln) substitution at the Furin protease cleavage site, was identified in one family that segregated with CL/P and both rib and vertebral hypersegmentation, mirroring that seen in Gdf11 knockout mice. In the second family in which CL/P was the only phenotype, a mutation in FST (encoding the GDF11 antagonist, Follistatin) was identified that is predicted to result in a p.(Cys56Tyr) substitution in the region that binds GDF11. Functional assays demonstrated a significant impact of the specific mutated amino acids on FST and GDF11 function and, together with embryonic expression data, provide strong evidence for the importance of GDF11 and Follistatin in the regulation of human orofacial development