Abstract
Plant-soil relations may explain why low-external input (LEI) diversified cropping systems are more efficient than their conventional counterparts. This work sought to identify links between management practices, soil quality changes, and root responses in a long-term cropping systems experiment in Iowa where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation. The 2-year system was conventionally managed and chisel-ploughed, whereas the 3-year and 4-year systems received plant residues and animal manures and were periodically moldboard ploughed. We expected changes in soil quality to be driven by organic matter inputs, and root growth to reflect spatial and temporal fluctuations in soil quality resulting from those additions. We constructed a carbon budget and measured soil quality indicators (SQIs) and rooting characteristics using samples taken from two depths of all crop-phases of each rotation system on multiple dates. Stocks of particulate organic matter carbon (POM-C) and potentially mineralizable nitrogen (PMN) were greater and more evenly distributed in the LEI than conventional systems. Organic C inputs, which were 58% and 36% greater in the 3-year rotation than in the 4-year and 2-year rotations, respectively, did not account for differences in SQI abundance or distribution. Surprisingly, SQIs did not vary with crop-phase or date. All biochemical SQIs were more stratified (p<0.001) in the conventionally-managed soils. While POM-C and PMN in the top 10 cm were similar in all three systems, stocks in the 10-20 cm depth of the conventional system were less than half the size of those found in the LEI systems. This distribution was mirrored by maize root length density, which was also concentrated in the top 10 cm of the conventionally managed plots and evenly distributed between depths in the LEI systems. The plow-down of organic amendments and manures established meaningful differences in SQIs and extended the rhizosphere of the LEI systems. Resulting efficiencies observed in the LEI grain crops indicate that resource distribution as well as abundance is an important component of soil function that helps explain how LEI systems can maintain similar or greater yields with fewer inputs than achieved by their conventional counterparts.
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Claims 13
Claim · model-written summary
LEI rotations matched or exceeded conventional rotation grain yield.
- Treatment
- 3-year and 4-year LEI rotationse0
- Outcome
- grain yieldse0
- Direction
- matched or exceedede0
- Comparator
- 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotatione0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
POM-C and PMN stocks were greater and more evenly distributed in LEI systems.
- Treatment
- LEIe0
- Outcome
- Stocks of particulate organic matter carbon (POM-C) and potentially mineralizable nitrogen (PMN)e0
- Direction
- greater and more evenly distributede0
- Comparator
- conventional systemse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stocks of particulate organic matter carbon (POM-C) and potentially mineralizable nitrogen (PMN) were greater and more evenly distributed in the LEI than conventional systems.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Organic carbon inputs were 58% greater in the 3-year than 4-year rotation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Organic C inputs, which were 58% and 36% greater in the 3-year rotation than in the 4-year and 2-year rotations, respectively, did not account for differences in SQI abundance or distribution.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Organic carbon inputs were 36% greater in the 3-year than 2-year rotation.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Organic C inputs, which were 58% and 36% greater in the 3-year rotation than in the 4-year and 2-year rotations, respectively, did not account for differences in SQI abundance or distribution.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Organic carbon inputs did not account for soil quality indicator abundance or distribution.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Organic C inputs, which were 58% and 36% greater in the 3-year rotation than in the 4-year and 2-year rotations, respectively, did not account for differences in SQI abundance or distribution.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Soil quality indicators did not vary with crop phase or date.
Not reportedOrgan / stage
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Surprisingly, SQIs did not vary with crop-phase or date.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Biochemical soil quality indicators were more stratified in conventional soils.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All biochemical SQIs were more stratified (p<0.001) in the conventionally-managed soils.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Surface POM-C and PMN were similar across three systems.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While POM-C and PMN in the top 10 cm were similar in all three systems, stocks in the 10-20 cm depth of the conventional system were less than half the size of those found in the LEI systems.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Conventional subsurface POM-C and PMN stocks were less than half LEI stocks.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While POM-C and PMN in the top 10 cm were similar in all three systems, stocks in the 10-20 cm depth of the conventional system were less than half the size of those found in the LEI systems.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Maize root length density was concentrated in the top 10 cm of conventional plots.
- Outcome
- maize root length densitye0
- Direction
- concentratede0
- Qualifier
- top 10 cme0
- Setting
- conventionally managed plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This distribution was mirrored by maize root length density, which was also concentrated in the top 10 cm of the conventionally managed plots and evenly distributed between depths in the LEI systems.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Maize root length density was evenly distributed between depths in LEI systems.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This distribution was mirrored by maize root length density, which was also concentrated in the top 10 cm of the conventionally managed plots and evenly distributed between depths in the LEI systems.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
Organic amendment and manure incorporation extended the LEI rhizosphere.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The plow-down of organic amendments and manures established meaningful differences in SQIs and extended the rhizosphere of the LEI systems.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
Claim · model-written summary
The authors interpret resource distribution and abundance as helping LEI systems sustain comparable or greater yields with fewer inputs.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Resulting efficiencies observed in the LEI grain crops indicate that resource distribution as well as abundance is an important component of soil function that helps explain how LEI systems can maintain similar or greater yields with fewer inputs than achieved by their conventional counterparts.”
e1“where grain yields of 3-year and 4-year LEI rotations have matched or exceeded yield achieved by a 2-year maize (Zea mays L.) and soybean (Glycine max L.) rotation.”
The same questions in other papers
rotation · yield · Zea mays (maize)Positive and negative results
253 papers in the same direction as this paper · 52 in the opposite direction · 16 reporting no difference from an alternative
- no effect
- positive
- positive
318 papers more in this group
See all 322 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.