Potential Nitrogen Contributions by Tropical Legume Summer Cover Crops in Mediterranean-Type Cropping Systems

Round 1

Reviewer 1 Report

1.     Materials and Methods:

      2.1. Field trial:  % Ndfa = [(δ15N reference plant – δ15 legume)/(δ15 N reference plant-B)] × 100； What does δ15 legume mean? Can you explain this mathematical formula in detail?

     2.2. Cover crop glasshouse trial: The last four paragraphs are all repetitive.

2.     Results:

      Lablab's biomass and nitrogen accumulation are very different in the greenhouse and field. What do you think is the reason?

      3.1. Glasshouse experiment:  Paragraph 2: “Shoot N content followed a similar trend to shoot biomass production, with the highest shoot N content observed in cowpea and lablab (both > 400 mg N plant-1). The low shoot N accumulation in balansa clover (22 mg plant-1) and barrel medic (151 mg plant-1) was reflective of their poor biomass production.” Nitrogen content is biomass multiplied by nitrogen concentration. biomass is large, nitrogen content is of course large. So there is no need to expand on that.

3.     Discussion: The results of the article estimate biological N2 fixation by legume cover crops in the summer fallow period in cropping systems in Mediterranean-type environments. It shows that cover crops can provide half of the nitrogen application of cash crops. However, inoculation, multiple watering and other practice during these two months have increased a lot of investment. Is it economical compared to using synthetic nitrogen? Is there any future impact on cash crop yield because of water use?

4.     References: One-third of the citations in the article are from the authors.

Author Response

Please see the attachment for the reviewer 1 and reviewer 2 comments and relevant changes that have been made throughout the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

I found the manuscript to be very well written and easy to follow.

In the Materials and Methods: Will readers know what B values mean?  I would suggest expanding the description of B values to say something like, "B values are required to quantify nitrogen derived from the atmosphere (%Ndfa) using the ¹⁵N natural abundance method."

On pages 4 and 5 where washing the soil is described.  Are the roots washed out of the soil, or is the soil washed out of the roots?  Consider rewording those sentences.

Repeating the field study portion of the experiment would greatly enhance any conclusions derived.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I have no more questions after the author's revision